The MusicBrainz (libmusicbrainz) C/C++ Library by MusicBrainz is a client library for developers. Using this library, developers can add MusicBrainz look-up capabilities to their applications. The MusicBrainz database contains a huge amount of music metadata, which is maintained by the MusicBrainz community.
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.
Innovation in web service APIs is not always technical, sometimes it's about money. Such is the case with Yahoo's announcement that later this year they will begin charging for usage of BOSS (Build your Own Search Service), their search web service for developers. Given that search revenue is typically ad-driven, and that advertising doesn't typically mesh with APIs, this has meant that search APIs have been one of the most challenging classes of APIs for providers to monetize. So it's notable to see how Yahoo has chosen to tackle this: via a 'utility' pricing model, somewhat akin to how infrastructure services like Amazon Web Services charge by usage.