The MusicBrainz C Library by MusicBrainz is a client library to assist developers in creating MusicBrainz disc IDs and freedbs from audio CDs. The MusicBrainz database contains a huge amount of music metadata, which is maintained by the MusicBrainz community.
Google has released version 3.0 of the YouTube Data API which includes new functionality and features including Topics API, Universal Search, Channel Bulletin Post, Full Subscriber List Management, and more.
In response to much feedback from the developer community, Microsoft has revamped the Bing Search APIs with a long list of new features. Not only do the new features expand the possibilities for using Bing within an app, a modern architecture should streamline integration and ease maintenance.