Here's the map of the Geek Pop 2011 Music Festival. On the website you click on the different stages, and then on the performers to listen to their songs, and download the free tracks. All the musicians are scientists (of one sort or another), and all of the songs are science-related (one way or another).
I've shared a few of my favorites from the 2011 Festival here. There's lots more music on the website.
If you enjoy the music, you might want to subscribe to the Geek Pop Podcast, or have a look at the Geek Pop YouTube Channel.