*bump*
So, have you tried
www.pandora.com? Very cool for finding new music. They don't have everything, but it's not bad. You create streaming "radio stations" based on your taste. I made a Camel station and a Gentle Giant station, and it plays stuff by them and by artists like them. It's got a fucked up idea of what Opeth is about based on Damnation, but what the hell. It's pretty cool.