Last.fm isn't bad, they usually have good recommendations when you look for similar artists, but they tend to list a lot of tracks they don't have. I've taken to just downloading entire albums even if I slightly like one song.
Oh yeah, I'm on last.fm too, but imeem had more full tracks. Last.fm also irritates me because Visual Kei and Video Game Music tags do not do well in the radio function. I go to search for Candy Spooky Theatre and it brings up some cheesy cutecore bunk. I guess I should just save up money and actually buy things...