Check out Pandora if you haven’t already. Basically you start by telling it a band you like, it plays you a song by them, and then it will walk you through similar songs by them and other artists. If you don’t like the songs it plays, you can tell it you don’t like them and skip them. It learns and suggests based on what you like. It’s free, and very cool.
It’s like TiVo, but not as cool