• AllCDCovers.com
• Amazon
• Last.fm
  
• ISBNdb.com
  
• Google Book Search APIs
• LibraryThing APIs
  
• OCLC Grid Services
• WorldCat Search API
• WorldCat Identities
• xID services
• xISBN
• xISSN
• xOCLCNum
  
• Registry Search
  
• Registry Detail
  
• Open Library API
  
• Talis Documentation

Article Data

• OpenDOAR
  
• arXiv.org

Map Mashup Data Sources

• Google Maps API
• Yahoo Maps API

Media Mashup APIs

• Blip.tv API
• Flickr API
  
• YouTube API