I like emusic.com. No DRM, but their selection is somewhat limited to the not-so-mainstream.
I found enough good music on emusic.com to keep a membership for 3 or 4 months, then I cancelled. I think it was worth it, considering they gave a bunch a free songs for signing up. You can find good bands if you like older stuff ('70s and '80s -- even '50s like Chuck Berry)...