Tomahawk is a free, cross-platform and open source music player that combines your local library of music with those of several popular music streaming services like Spotify, Grooveshark, SoundCloud, Last.fm, YouTube and more to offer a unified music listening experience. And it doesn’t stop there – by hooking up with your Jabber or Google account you can play music from your friends’ libraries too, provided they’re also running Tomahawk.