A través de Digg me encuentro con un completo listado de APIs Web 2.0, seguro que os resultará muy útil, lo reproduzco aquí:
Advertising
| Google AdSense | Administración de publicidad con Adsense |
| Google AdWords | Anunciarse en buscador Google |
| Microsoft adCenter | Servicios de publicidad online de Microsoft |
| UrlTrends | Optimización de búsqueda y seguimiento de enlaces |
| Wordtracker | Search engine optimization services |
| Yahoo Ads | Administración de anuncios online de Yahoo |
| Yahoo Search Marketing | Plataforma de publicidad en búsquedas |
| Answerbag | Questions and answers service |
| Blogwise | Blog and feed search service |
| SplogSpot | Database of spam blogs |
Blog Search
| Blogwise | Servicio de búsqueda en blogs y feeds |
| SplogSpot | Base de datos de blogs de spam |
| Tailrank | Blog search and news aggregation service |
| Technorati | Servicio de búsqueda en blogs |
Blogging
Bookmarks
| Blogmarks | Social bookmarking |
| del.icio.us | Social bookmarking |
| linkaGoGo | Social bookmarking service |
| Ma.gnolia | Social bookmarking service |
| OnlyWire | Social bookmarklet service |
| Shadows | Social bookmarking and community |
| Simpy | Social bookmarking |
Calendar
Chat
Community
| Blue Dot | Content sharing community |
| coRank | Distributed user reviews service |
| Facebook | Social networking service |
| PartySpark | Social events service |
| RockYou Super Wall | Content sharing platform within Facebook |
| Twitter | Community site |
Email
Enterprise
Events
| Eventfinder | Calendario de Eventos |
| Eventful | Events discovery and demand |
| Spraci | Events and clubs database |
| Upcoming.org | Collaborative event calendar |
| Zvents | Local events search and community |
Financial
Government
| Cicero | Lookup service for US elected officials by address |
| Civic Footprint | Political geography lookup for Illinois |
| Democracy In Action | Advocacy services for nonprofits |
| FedSpending.org | Database of US government spending |
| Follow The Money | Database of US campaign contributions |
| GovTracker | Rhode Island state data services |
| LOUIS | US federal documents database |
| Open Patent Services | European Patent Office web services |
| Sunlight Labs | US Congress database service |
| TheyWorkForYou | Track the UK Parliament |
| Who is my Representative | Database of US congressional representatives |
Internet
| Alexa Site Thumbnail | Thumbnail images of web site home pages |
| Alexa Top Sites | Web site traffic rankings |
| Amazon EC2 | Elastic Compute Cloud virtual hosting |
| Clicky | Servicio de estadísticas para sitios web |
| Compete | Internet web site metrics and analytics |
| Cordurl | Geo coordinate translation |
| Dapper | Service for API creation |
| Domain Tools | Internet domain name lookup |
| Durl.us | URL shortening |
| Ecommstats | Web analytics |
| Hostip.info | IP lookup |
| HTML2PDF | HTML to PDF conversion |
| Internet Archive | Non-profit Internet library |
| IP Address Lookup | Determine IP address from domain name |
| Mint | Web site metrics and reporting |
| Mon.itor.us | Web site monitoring services |
| MyNotify | Feed publication |
| Nenest | Web forms and application framework |
| Outune | Web map engine |
| Pingdom | Web site monitoring and reporting |
| Qurl | Redirección de URL |
| SoftLayer | Systems management and monitoring |
| UnAPI | Proposal for web clipboard |
| W3Counter | Web site metrics tools |
| Webride | Attaches discussions to any site |
| WebThumb | Thumbnail image generation |
| Windows Live Custom Domains | Web site administration |
| Yahoo Site Explorer | Web site analysis service |
Job Search
| Indeed | Job search services |
| SmashFly | Job board posting service |
Mapping
| ArcWeb | Mapping and GIS services |
| BigTribe | Location based advertising |
| deCarta | Location-based services |
| EarthTools | Web services for geographical information |
| FeedMap | Blog geo-coding |
| Garmin MotionBased | GPS services and mapping |
| geocoder | Geocoding services for US |
| geocoder.ca | Geocoding services for Canada |
| GeoIQ | Geospatial analysis and heat mapping service |
| GeoNames | Geographic name and postal code lookup |
| GetMapping | Aerial photography and mapping service |
| GlobeXplorer | Mapping services |
| Google Maps | Mapping services |
| HopStop | Mass transit and walking directions |
| iShareMaps On Demand | UK Postcode Geocoder |
| Map24 AJAX API | Mapping services |
| Mappr | Photo mapping |
| MapQuest | Online mapping service |
| Mapstraction | Mapping API abstraction layer |
| MetaCarta | Location and geotagging services |
| Microsoft MapPoint | Mapping services |
| Microsoft Virtual Earth | Mapping services |
| Multimap | Global online mapping service |
| NASA | Satellite mapping images |
| Naver Maps | Korean mapping service |
| Nearby.org.uk | Geocoding service for UK |
| Ontok | Geocode any US address |
| OpenLayers | Mapping API abstraction layer |
| OpenStreetMap | The Free Wiki World Map |
| Platial | Collaborative geographic service |
| Plazes | Location discovery service |
| Poly9 FreeEarth | 3D mapping service |
| Pushpin | Mapping service |
| Urban Mapping | Urban geo-spatial data services |
| USGS Elevation Query Service | Determine elevation based on latitude and longitude |
| ViaMichelin | Mapping, directions, and travel booking |
| Wayfaring | Map creation and sharing service |
| WHERE GPS | Mobile GPS widget platform |
| Where Is Tim Web Service | Location tracking |
| Where2GetIt Geospatial | Non-mapping geospatial services |
| Where2GetIt SlippyMap | Online mapping service |
| Whereis | Australian and New Zealand mapping service |
| Wigle | Wireless network mapping |
| Yahoo Geocoding | Geocoding services |
| Yahoo Map Image | Map image creation service |
| Yahoo Maps | Mapping services |
| ZeeMaps | Embedded maps and international geocoding |
| ZoomIn | Australian mapping service |
Media Management
| BBC | Multimedia archive database |
| Grouper Video | Video sharing service |
| Orb | Digital media remote access and management |
| Phanfare | Photo and video sharing service |
| Streamload | Online media storage |
Medical
| cPath | Medical database lookup |
| Kegg | Bioinformatics data services |
| NCBI Entrez | Life sciences search services |
| SeqHound | Bioinformatics research database |
Messaging
| 411Sync | SMS, WAP, and email messaging |
| Aql | SMS solutions portal |
| Clickatell | SMS Messaging services |
| Jaiku | Social messaging service |
| Mobivity | SMS marketing messaging service |
| Movil | SMS messaging |
| PartySync | Messaging services |
| Sabifoo | IM to RSS conversion service |
| SmsBug | SMS messaging services |
| StrikeIron Global SMS Pro | SMS messaging services |
| StrikeIron Mobile Email | Mobile email messaging service |
| Textamerica | Moblogs |
| Trekmail | Messaging services |
| Twittervision | Location based data for the Twitter service |
| Userplane | Communication software for online communities |
| Vazu | SMS messaging service |
Music
| AOL Music Now | Music playlist management |
| Digital Podcast | Podcast search |
| Faces.com | Photo and media sharing service |
| Feedcache | Feed caching service |
| Freedb / CDDB | Online CD catalog service |
| Last.fm | Music playlist management |
| MP3Tunes | Music services |
| MusicBrainz | Music metadata community service |
| MusicDNS.org | Music fingerprinting service |
| MusicMobs | Social music service |
| OpenStrands | Music recommendation and discovery |
| Rhapsody | Online music services |
| SeeqPod | Music recommendation service |
| SNOCAP | Digital music marketplace |
| Soundtoys | Visual artists works repository |
| Tunelog | Music metadata management |
| WebJay | Music playlist management |
| Winamp | Customizable music player |
| Yahoo Music Engine | Desktop music player |
News
| AmphetaRate | News aggregator |
| ClearForest Semantic Web Services1 | Natural language processing tools |
| Daylife | Online News Service |
| Digg | |
| Findory | Personalized news aggregation |
| Macromedia News Aggregator | Data access service |
| Moreover | News delivery |
| NewsCloud | Social news service |
| NewsIsFree | Online news aggregation |
Office
| Backpack | Online information manager |
| Big Contacts | Web based contact management |
| EditGrid | Online spreadsheet |
| Google Documents List | Document management services |
| Google Spreadsheets | Online spreadsheets |
| Numbler | Online spreadsheet service |
| SlideShare | Presentation sharing community |
| Zoho | Online office suite |
Photos
| AOL Pictures | Online photo management |
| Buzznet | Photo sharing |
| Flickr | Photo sharing service |
| Fotolia | Royalty free stock photos |
| Google Picasa | Photo management and sharing service |
| imageLoop | Animated slideshow service |
| Panoramio | Photo upload site with organizer |
| Pixagogo | Online photo services |
| Riya | Photo search |
| ShutterPoint | Stock photography service |
| Smugmug | Photo sharing service |
| Snipshot | Online photo editing service |
| WebShots | Photo sharing service |
| Yahoo Photos | Online photo service |
| Zoto | Photo sharing service |
Recommendations
| Criteo | Distributed recommendation service |
| EasyUtil | Recommendation service |
| RapLeaf | Portable ratings system |
| Yelp | Local user reviews and city guides |
Reference
Search
Shopping
Storage
| Amazon S3 | Online storage services |
| Box.net | Online file storage |
| MoveDigital | File delivery and management services |
| Omnidrive | Online storage services |
| Open Xdrive | Online data storage service |
| Openomy | Online file system |
| Tagalag | Email tagging |
| TagFinder | Tag extraction service |
| Tagthe.net | Tag recommendation service |
| TagTooga | Tag based Internet directory |
Video
| Truveo | Video search |
| Blinkx | Video search |
| Dave.TV | Video distribution network |
| LiveVideo | Video repository and user community |
| Revver | Video services |
| Veoh | Virtual television and video network |
| Video Detective | Film trailers, cast, images, and related information |
| Yahoo Video Search | Video search |
| YouTube | Video sharing and search |
Widgets
| ClearSpring | Widget creation, distribution, and tracking services |
| Google Gadgets | |
| Netvibes | Personalized home page with widgets |
| Pageflakes | Personalized start page and widgets |
| Serence Klip | Desktop gadgets |
| SpringWidgets | Widget platform |
| TagWorld | Social web services |
| Windows Live Gadgets | Online gadgets service |
| Windows Sidebar Gadgets | Desktop gadgets |
| Yahoo Widgets | Desktop widgets |
| Yourminis | Personalized start page |
WIKI
| DBpedia | Interfaz estructurada para solicitudes a Wikipedia |
| JotSpot | Utilidad de colaboración con estilo Wiki |
| PBwiki | Consumer wiki farm |
| WikiMatrix | Servicio de búsquedas y comparaciones en Wiki |
vía: Techmagazine