1 - 9, A - B; Updated

Italic = new to this list.

1001 - Flickr update service - Images
1000tags - Tag cloud based search - Search
123businesscards - Design & print your business cards on demand - Software
1millionsentencesxista - Buy a sentence and increase traffic - Marketing
20culture - Article on Web 2.0 design trends - About
20websites - Categorized lists of Web 2.0 phenomena - About
23hq - Store, share & manage photos - Identity
24eyes~ - Personalize your start page or subscribe to someone else's - Startpage
24sevenoffice - Web-based crm & erp - CRM
2prong - Get email address for 24 hrs - Communicate
2Recall* - Record calls on any phone (USA) - Communicate
301url - Shorten your url - Software
30boxes - Manage & share calendar - Office
30daytags - Fresh tagclouds - Tag
30gigs - Store your data - Store
31left - Publish and share new year's resolutions - Publish
37signals* - Basecamp, Backpack, Writeboard, Ta-da List - Software
3B - 3D web browser - Browse
3bubbles - Add chat to your blog - Communicate
3jam - One to many texting - Communicate
3spots - Lists many Web 2.0 apps & websites - About
3voor12~** - Profile yourself & share media - Multimedia
43deals - Find best deals - Ecommerce
43people - Tag based matching & dating - Community
43places - Publish & share stories about places - Community
43things - Publish, share, find your goals - List
4shared - Upload & share files - Organize
5min - Upload, explore & share how to-videos ('videopedia') - Knowledge
5minutefriend - Videochat for 5 minutes with random users - Communicate
6-Clicks - Add keywords to websites - Bookmark
71miles - Read & contribute to regional travel portals - Community
7tipson - Browse & share tips - Knowledge
8by1 - Share your wish - List
97tags - Own a tag exclusively - Tag
9cays - Group email2web - Communicate
9minutesoffame - Submit your blog & get 9 minutes exposure - Marketing
9rules - Validate & share links to content - Bookmark
A9** - Clustered search - Search
Abaqueinside - Catalogue ware - Software
Abazab - Upload & share your vids - Video
Abcde… - Get the longest email-address - Communicate
Abiword - Web-based word processing (download) - Office
Abouturl - Aggregates many site tests - Software
Aboutus - Wiki about websites - List
Abstractmouse - Social bookmarking - Bookmark
Academiclive - Search academic articles - Search
Accoona - A.I. Enhanced search - Search
Activeallowance - Kids & parents manage kids' allowances - Finance
Activecollab - Collaboration & project management tool (free) - Software
Adaction - Search me - Search
Adahead - Marketplace for advertisers & affiliates - Marketing
Adaptiveblue - Collect & manage favourite things - List
Addictingclips - Upload, watch & share multimedia - Multimedia
Addthis - Collect 'all' information with one button - Bookmark
Adgenta - Add ads to your site, blog or rss feed - Ecommerce
Adgridnetwork - Ad exchange - Marketing
Admob - Buy or sell mobile advertising - Marketing
Adoppt - Publish & share - Community
Adultswim - Episode previews, games, community - Video
Aduna~ - Visualize search results - Search
Adveracious - Digg advertising news - Rate
Advisorgarage - Connects entrepreneurs to advisors - Economy
Aegeetv~ - Create & share video (for European students) - Video
Aftervote - Meta search inc several rankings - Search
Agester - Let other users tell how old you look - Community
Aggregateknowledge - Recommendation engine - Collaborate
Agloco - Subscribe to portal & get paid for it - Marketing
AI3 - Articles & lists re semantic softwares - About
Aidpage - People help people - Economy
Aim - Myspace for AOL users - Community
Airset - Manage & share calendars, contacts, groups - Organize
Airtroductions - 8 miles high dating - Date
Ajax - Mozilla developer community - Software
Ajaxian** - Ajax blog - About
Ajaxilicious - Share your movies thru RSS - Video
Ajaxload - Generates animated Ajax load gifs - Software
Ajaxpaterns - Ajax developers portal - Software
Ajaxshowcase - Aggregates Ajax applications - Software
Ajaxsketch - Create drawings & diagram - Design
Ajaxwhois - Results while you type - Search
Ajaxxls - Spreadsheet in Ajax - Office
Ajchat - Create chat rooms - Communicate
Albumart - Search for CD and DVD covers - Search
Alertbear - Customize your feeds - RSS
Alesti - Feed reader - RSS
Alexadex* - Buy & sell shares in sites - Game
Alexscoupons - Find coupon deals - Marketing
Alivebroadcast - Upload & share personal webcam photos - Images
Alkemis - Map mash-up - Geo
Allconsuming - List & share everything you like - List
Allfreecalls - Make free calls from the USA - Communicate
Allmydata - Store & share your data - Store
Allmyfavorites - Social bookmarking - Bookmark
Allpeers - Upload & share your media (Czech) - Multimedia
Allspotsmarket - Sports stock market - Gamble
Allthingsweb2 - Extensive list of Web 2.0 companies, based on my first listings - About
Allyoucanupload - Image storage - Store
Allyourwords - Associate & share words with links - Bookmark
Almondrocks - Share feeds - RSS
Alpinaut - Search route maps - Search
Altsearch - Categorized list of Web 2.0 companies that are also in THIS list - About
Amateurillustrator - Publish, rate & rank illustrations - Community
Amazon* - Shop, sell, review & rank - Ecommerce
AmazonEC2 - Provides resizable computing capacity - VAS
Amazontreemap - Treemap example with "All Digital Cameras"; many more at this link - Data
Amazonwebservices - Unlimited storage - Store
Amaztype - Create typeface from word-relevant book covers (Amazon mash-up) - Images
Ambedo - Bookmark, tag & search - Search
Amberjack - Create & publish site tours - Software
Ambientdevices* - Datacasting inc. interfaces - Data
Amiamo - Find things & people you like - Community
Amiestreet - Market place for original music - Audio
Amiglia - Publish & share family trees, photos, maps… - Community
Amigo - Matches advertisers with email newsletters - Marketing
Amigofish - Rate, recommend & share podcasts - Audio
Amvona - Publish, manage & share your photos - Images
Ándale - Small online business sales tools - Ecommerce
Aniboom - Create, upload, rate & rank animation movies - Video
Annologger - Publish & share announcements - Publish
Annotea - Create & share metadata - Knowledge
Anobii - Publish, share & discover booklists - List
Anoox - Majority vote optimized search - Search
Anothr - Manage & read feeds in Skype messenger - RSS
Answers - Best answers to your questions - Knowledge
Apartmentratings - Rent after reading tenant's review & rating - Ecommerce
Apollo - Adobe RIA development platform - Software
Applian - Capture streaming audio & video - Software
Approver - Share & work on documents online - Office
Arcaplay - Rate & share games - Game
Artfaceoff - Strives to emulate natural intelligence thru accumulated experience - Rate
Askalexia - Ajax interface to Alexia.com - Search
Askeet - Ask & answer it - Knowledge
Askitonline - Create & conduct online surveys - Survey
Asktheworld - Q&A - Knowledge
Askville - Q&A by Amazon - Knowledge
Askvox - Write a question & hear the answer - Knowledge
Asoboo - Find people & places in your city - Collaborate
Associatedcontent - Produce & publish content, get paid - Economy
Asterisk* - Open source phone system (free) - Software
Ataja - Shorten your url - Software
Atiki - Tag based feed search - RSS
Atlarge - Read & write about web access at airports - Wi-fi
Attendr - Mash-up your conference or party - Community
Attensa - Read & share feeds enterprise-wide through Outlook - RSS
Attentiontrust - Advertising based on mutual understanding - Marketing
Attentv - Subscribe to other persons' clickstreams or start your own station - Video
Auctionmapper - Find auctioned goods nearby (mash-up) - Ecommerce
Audioclipping* - Search AV (German) - Search
Audiodizer - Text2Speech podcasts from your blog - Audio
Audiosnacks - Create, share & download audio travel tours - Audio
Audiri - Recommend & share your media - Multimedia
Autospies - Digg cars - News
Averageshoveler - Game & RSS news mash-up - Game
Avidbeauty - Share photos & sounds - Multimedia
Avvenu - Remote access to your computer - Office
Avvo - Something legal (stealth) - VAS
Aytozon - Comparison shopping from Amazon & Ebay - Ecommerce
Aytozon - Ebay + Amazon metasearch - Search
Azareus - Distribute bandwidth & share content - Software

B2evolution - Blog solution - Publish
Babble - Word game community - Game
Backbase* - Ajax applications - Software
Backfence - Publish & share community news - Rate
Backflip - Social bookmarking - Bookmark
Backseatplayground - ARG using GPS for gameplay in real world (documentary video) - Game
Badged - Add your social networking badges to your blog - Community
Baeboo - Shop comparison - Ecommerce
Bagbooroworsteal - Get a handbag each month for a few bucks & let it circulate - Economy
Ballbug - Memeorandum for baseball - News
Barablu - Free or cheap calls, IM, chat etc. thru mobile & web - Communicate
Barcamp - Ongoing interactive event - Collaborate
Barcardz - Network in real life - Community
Basecamp - Manage your projects - Organize
Bashr - Wikipedia, Flickr & Delicious mash-up - Search
Battleout - Challenge & vote for best, biggest etc. whatever - Community
Bbpress - Publish & manage your forum - Communicate
Beamfile - Email big files - Office
Beanrocket - News reader - RSS
Bebo - Find back school & college friends - Community
Bebop - Compare music calendar against your iTunes catalogue - Audio
Become - Collective shopping search - Search
Beedeo - Upload & share videos - Video
Beeplet~ - Set up reminders & get alerts - RSS
Beetagg - Scan branded sema code with your cell to get access to website - Marketing
Beetobee - Digg what works in B2B marketing (also offers solution for enterprise 'thought leadership communities' - cf. http://www.beetoobee.com/productsite/) - Rate
Beggr - Give me your money - Finance
Begreen - Here it's easy being green - Community
Beinsync - Backup & access all files anywhere - Store
Bessed - Search & blog - Search
Bestofbest - Categorized best of best 2.0 websites - About
Betamarker - Digg software - Rate
Betbug - Betting exchange - Gamble
Betbull - Betting exchange - Gamble
Betdaq - Betting exchange - Gamble
Betfairgames - Bet on poker and blackjack games - Gamble
Betfairpoker - Poker community - Gamble
Betmate - Betting exchange - Gamble
Betocracy - Create your own decision markets - Gamble
Betonbet - Bet on sports, poker & casino games - Gamble
Betsgowild* - Cash-free betting community - Gamble
Betsson - Betting exchange, poker & casino tournaments - Gamble
Betterdesktop - Share usability tests - Design
Bettingmarket - Article on P2P betting - About
Bibli - Publish & share texts - Publish
Bibliochat - Get book excerpts and reviews, and discuss books - live - Community
Bibliophil - List your books & share - List
Bibsonomy - Share bookmarks & literature lists - List
Bibster - Search, share & manage bibliographic metadata - Search
Big - Big search results - Search
Bigbluesaw - Submit cad design & get product delivered - Personal manufacturing
Bigcartel - Start, review & recommend online shops - Ecommerce
Bigcartel - Web stores for creative people - Software
Bigcite - Publish & share quotes - Publish
Bigcontact - Publish your videos & mp3s - Multimedia
Bigcontacts - Upload, annotate & share your contacts - Office
Biggerboat - Search entertainment - Search
Biginjapan - Social media tools - Software
Bigoven - Publish & share recipes - Publish
Billhighway - Budget, collect, pay between roommates, fraternities, etc. - Finance
Billmonk - Manage debts - Economy
Billq - Keep track of your bills - Finance
Billster - Track where your money goes - Finance
Bioteams* - Blog on team dynamics & virtual collaboration - About
Birthdayforever - Manage & share your wishlist & photos - List
Bitbomb - Web2SMSs reminders - Office
Bitsofnews - Submit, read, rank & discuss news - Rate
Bittercyclist - Bicycle accident map & community; map mash-up - Geo
Bittorrent - Share files & bandwidth - Office
Bitty - Embed content from web services - Publish
Bitwine - Get or give video advice for a price - Knowledge
Bix* - Create & vote for content, and win - Multimedia
Bixee - Job finder - Employment
Biznik - Business network - Community
Blabb - Social bookmarking - Bookmark
Blackplanet - Community for African-Americans - Community
Blast - Promote your site for free - Marketing
Blastfeed - Only get the feeds that matter to you - RSS
Bliin~ - Share your experience in photos, videos, text etc - Geo
Blinkbits - Share knowledge - Knowledge
Blinkist - Social bookmarking - Bookmark
Blinklife*** - Social email - Communicate
Blinklistsocial - Lists of 2.0 websites - About
Blinkr - Digg design - Rate
Blinksale - Web-based invoicing - Finance
Blinkx - Personalized epg - Video
Blip - Get video & podcasting on your blog - Publish
Blipfoto - Publish your phlog - Publish
Blipstar - Create your own store locator - Geo
Blish - Buy or sell your media - Ecommerce
Bliss - Customize game to couple’s needs - Game
Blnk - Publish & share your profile and make new friends - Community
Blobber - Communicate with other site visitors - Communicate
Blockhunter - Find, sell or let a home & avoid real estate agents - Ecommerce
Blockrocker - Buy & sell thru classifieds; map mash-up - Ecommerce
Blocksavvy - Habbo for adults - Game
Blogabond - Publish your travel blog (map mash-up) - Publish
Blogbar - Searches your blog and the web - Search
Blogbeat - Compare websites' Alexa rankings (formerly known as Alexaholic) - Data
Blogbridge - Feed reader - RSS
Blogburst - Syndicate blogs to mainstream media sites - Publish
Blogbuy - Social market place - Ecommerce
Blogbuzzmachine - Blog search - Search
Blogcatalog - Blog directory - Search
Blogcheese - Publish video on your blog - Video
Blogcode - Start blog & find similar ones - Publish
Blogdex - Folksonomied blog topics selection - News
Blogdigger - Search blogs - Search
Blogelo - Rate & share websites - Bookmark
Blogexpress - Feed reader - RSS
Bloggerkit - Let Amazon exploit your blog - Ecommerce
Bloggersnap - Add your webcam snapshot to any blog - Publish
Bloggoggle - Categorize & rate pro bloggers - List
Bloginfluence - Let your art compete with other artists' submissions - Rate
Blogladder - Create & maintain your blog - Publish
Bloglebrity - Compute your blog's influence - Fun
Bloglet - Blog update notifications thru email - Publish
Bloglines - Feed reader - RSS
Blogmailr - Use email to send blogposts - Publish
Blogmarks - Social bookmarking - Bookmark
Blogmemes - Vote for & share memes - Rate
Blogniscient - Rate your influence in the blogosphere - Rate
Blogoforum - Categorize your forum by tagging - Communicate
Blogprinting - Publish, print & sell it - Publish
Blogpulse - Search blogs - Search
Blogr - Publish & share your media - Publish
Blogrovr - Get links to context relevant blog articles while you're browsing - Search
Blogs - Notification2email - Publish
Blogscope - Blog analytics software - Data
Blogsitter - Find (or offer yourself as) a blog co-publisher - Publish
Blogspirit - Blog solution - Publish
Blogstickr - Add fake stickers to your blog - Fun
Blogtalkradio - Host your own phone-in talkradio show online - Audio
Blogtelevision - Search videos in blogosphere - Video
Blogtronix - Blogging & corporate community software - Community
Bloodee - Digg horror - Rate
Bloqr - Publish & share blogs & media - Publish
Blotter - Graph your blog's popularity - Software
Bloxor - Maintain & use your blogroll online - Publish
Blubbry - Publish, share or listen to podcasts - Audio
Bluechipexpert - Profile yourself, invite friends & recruit other professionals, and get paid - Employment
Bluedot - Social bookmarking - Bookmark
Bluedot (formerly: Blue) - Find & share - Search
Bluegrind - Have your personal news anchor reading the news to you - News
Bluepuddle - Create & enrich maps - Geo
Bluepulse - Internet 2 cell phone - Software
Bluesmiley - Manage your online life - Office
Bluetie - Collaborative Office-like toolkit - Collaborate
Blufr - Multi-player trivia knowledge game - Game
Blummy - Manage your bookmarks - Bookmark
Blurb - Turn your blog into a book - Publish
Bmaccess - Social bookmarking with thumbs - Bookmark
Boardreader - Forum & bulletin board search engine - Search
Boardtracker - Search forums - Search
Bofunk - Pick up content for your blog - Multimedia
Bolt - Watch, upload & share media - Store
Boober~ - Get or bid for giving loans - Finance
Boo-box - Add shopping links to your postings & make money on them - Marketing
Bookmarktracker - Social bookmarking - Bookmark
Bookmooch - Exchange old books - Community
Bookr - Create & share photobook with Flickr images - Images
Bookrevyoo - Social book review community - Community
Booksforschool - Buy & sell used text books - Ecommerce
Bookswellread - Publish & share book reviews - Publish
Boompa - Show your rides & find guides & parts to improve them - Economy
Bordee - Instantly create message board for your page - Software
Boredwealth - Get paid to surf ("Alladvantage.com resurrected") - Economy
Bouldr - Share climbing (map mash-up) - Community
Bountee - Design, buy & sell T's - Ecommerce
Box - Store & share data - Store
Boxbe - Use as your public address, let advertisers pay to reach you - Communicate
Boxed* - Build calendars out of all sorts of online sources - Office
Boxxet - Personalize your incoming content - Startpage
Bozpage - Web 2.0 sources - About
Brainkeeper - Capture, distribute & collaborate on corporate knowledge - Knowledge
Brainreactions - Participate in brainstorms & share ideas - Knowledge
Brandgossip*~ - Find what people say about your brand - Search
Brands2.0 - Traditional brands in 2.0 design style - Fun
Breakinglocals - Local artists and fans community - Audio
Brickfish* - Submit, vote for & review content, and get rewarded for it - Publish
Brightcove - Syndicate & get videos for your website - Video
Britepic* - Add extra content & intelligence to your online pics - Images
Britney - Recommend, publish & digg next big hits - Rate
Broadbandgenie - Find best provider - Ecommerce
Broadbandsports - Upload & share sports videos - Video
Broadramp - Multimedia management solutions - Software
Broadsnatch - Share multimedia - Multimedia
Brokenotbeat - Donate to a needy person each day - Economy
Browse3D - 3D web browser - Browse
Browsershots - View thumbs of your website in all browsers - Design
Browsr - Social directory - Startpage
Browster - Search & browse instantly - Search
Browzar - Surf anonymously - Browse
Bryght - Create & maintain a community - Store
Bstir - Serve a random posting from your archive - Publish
Bubble20snarkgroup - Everything against Web 2.0 - About
Bubbleguru - Record & publish your videos (featuring you) - Publish
Bubbleply - Add bubbles to media & share them - Video
Bubbles - Launch frequently used sites in your system tray from a light browser (download) - Browse
Bubbleshare - Phlog, share, add audio captions - Multimedia
Bubblesnaps - Add balloons to your pics & share them - Publish
Bubblr - Create & share photo strips - Publish
Bubblus - Brainstorm together online - Knowledge
Buddymapping - Assemble your friends on a map & publish it - Geo
Buddymarks - Social bookmarking - Bookmark
Buddyping - Find friends & events locally (map mash-up) - Office
Budgettracker - Track your finances - Finance
Builtsmarter - Modular site (re)construction software - Software
Bulletin* - Share data & mash them up with geo information - Geo
Bulletprooflinks - Share tutorials, tools & templates - Design
Bullpoo - Find, share & collaborate on investment information - Finance
Bunchball - Play games with your friends - Game
Businesssoftware - Article on running a business on Web 2.0-based software - About
Busythumbs - Post & share text & photos from cell to blog - Publish
Butlerbob~ - Advertise, find, book & buy concierge services - Ecommerce
Butterfat - Traceroute map mash-up - Communicate
Butterfly~ - Bookmark & annotate - Bookmark
Buttonator - Drag, drop & share web buttons - Design
Buurtlink~ - Find people, places & news in your hood - Community
Buxfer - Keep track of shared costs - Finance
Buyyourfriendadrink - Buy or redeem drinks thru cell phone code - Economy
Buzzdash - Create & share polls - Survey
Buzzfeed - Memetracker goes Boingboing - News
Buzzillions - Buy & review products - Ecommerce
Buzzingo - Buzz notifier (Yahoo + Feeling Lucky mash-up) - News
Buzzlogic - Monitor, map, measure & manage your rep in social media - Identity
Buzznet - Share videos & photos - Multimedia
Buzzshout* - Review & rank Web 2.0 companies - About
Buzzwordhell - Rate & condemn - Fun
Byoms - Personalized IM search agents on your cell - Search

Updated 070527.