I’ve stumbled across a great web site for free music: Jamendo. All the music on the site is released under a creative commons licence, which essential lets you do anything with the music, as long as you don’t claim its your original idea and credit the true author (essentially ensures you can’t lie).
There is currently 3281 albums published on it. Although many of them aren’t full length albums, your getting a lot more than you have paid for.
The best ‘artist’ I have found on it so far is t r y ^ d (aka tryad). There music is worth a listen.