Check out podesafeaudio.com
This site aims to provide a location where musicians can upload music under the Creative Commons License for use in Podcasts, Mashups, Shoutcasts, Webcasts and every other kind of ‘casting’ that exists on the ‘net.
I just subscribed to their podcast in iTunes and they’ve got some really good music on there. Plus, they’ll probably be an important part of my soon to be released podcast about songwriting and music publishing.