The official 7digital Android SDK affords to integrate music charts, metadata, streams, and purchases into an Android application. 7digital is a service that offers over 30 million music tracks with curated recommendations. What author Ling Khor created to demonstrate how his project works, was the 7digital Android Buy Button. This sample allows users to buy a track without leaving the app. This is the project: https://github.com/7digital/7digital-android-buy-button-demo
Full API documentation available at: http://7digital.github.io/7digital-Android-SDK/apidocs/
For music fans who enjoy listening to playlists on their laptops or desktops, Tomahawk is a music player with a few extra bells and whistles that may be of some interest. It's an open-source, cross-platform music player, which means it enables a user to play music stored on their own hard drives as well as from a variety of other music sources like Spotify, SoundCloud, YouTube and more. The Toma.hk API makes this functionality available to developers or users to add songs to websites.
There's been some great new music mashups coming down the pipe lately. We'll highlight some of the better ones below, including a music search engine, local music events, lyrics lookup, a Spotify video playlist app (yes, there's a Spotify API) and a fun "name that tune" game. The most popular music API, the Last.fm API, is featured multiple times, as is the YouTube API, which has become a favorite of music mashups.