The Decibel C# SDK allows developers to query the Decibel API to return music metadata. Calls to the Decibel API are made through query objects, which take care of all the logic involved in running a REST query, which can then be used to integrate Decibel data into an application.
In our writeup on Seevl, we mentioned that using the Seevl API to add context to Youtube videos would be ideal. Well, apparently, it was thinking along exactly those same lines. I talked briefly with Alexandre Passant, who is one of the main people at Seevl, and we talked about the company's new mashup, and its future plans for the API.
Last December, Senzari launched the MusicGraph music recommendation and data access engine as well as the new MusicGraph API. Earlier this month, Senzari opened the MusicGraph API to the public, unveiling the API at the first-ever annual SXSW Music Hackathon Championship. Among the apps included in the list of overall grand prize finalists is Party Play which uses the MusicGraph API to create "a dynamic DJ for parties."
Stereomood is a streaming music service that gives recommendations. To start, it uses a list of moods, each of which have an associated playlist. While playing songs, users can like or ban songs, much like Last.fm or Pandora. The Stereomood API allows full access to the site's functionality to developers, allowing developers to make fully usable clients on any platform.