I was playing with Pandora the other day, looking for new bands to listen to and download to my iPod. If you haven’t tried it yet, give it a shot; it’s a recommendation engine that uses acoustic and song arrangement properties to classify music and "suggest" music to you based on what you like.
It’s a bit hit or miss sometimes — I first tried ColdPlay, and the bands that were pulled up were quite good. I then tried a specific song, "What I Got" by Sublime, and the music that resulted was a bit disappointing. Still, overall, I enjoyed the app. If nothing else, it’s good for optimizing your LimeWire treasure hunts.