The Rdio Web Service Ruby SDK by Rdio allows API interaction to implement audio and music streaming. Examples show how to authorize user credentials and create playlists from artists. Rdio has been recently acquired by Pandora. For integration updates, follow @Rdio on Twitter.
The Punkrock.org API uses POST and GET calls that allow a user of your app to access their own user info on Punkrock.org, including friends, mail, notifications and allows them to upload photos. Requesting an API key is required for access to services.
Think the social web is big? When it comes to connecting Twitter, Facebook and others to the rest of the web, APIs are there to do the heavy lifting. The category continues to explode, already surpassing the number of social APIs added last year. Our directory currently lists 558 social APIs, with nearly 200 added this year.
I love Rdio. All the music I want to hear (that happens to be available in their library) for $10 a month. It gets better. I can download the songs to the mobile Rdio apps for offline listening. Even better still, there's an Rdio API and it's pretty rich, as described by Rdio's Ian McKellar in the video below.