Just stumbled on the Music Genome Project at
www.pandora.com. I've only been playing with it for a day or so, but so far, I'm impressed. Feed in a favorite artist or two, and it suggests other music you might like. Along the way, you can refine by indicating whether you like the suggestions or not. Give it a spin (oops..anachronistic references to the old days of vinyl are a symptom of my age).