Most readers probably know Pandora, but maybe there are still some who don't. Pandora is a wonderful music service that lets you listen to a music selection tailored to your taste. You start by entering the name of a band or a title that you like. Pandora then starts playing songs of a similar style. You can rate any song you hear to educate Pandora about your taste, so over the time the selection becomes better and better.
You can read a little bit about the underlying magic here. I assume in addition to the results from The Music Genome Project they utilize collaborative filtering (like Amazon's "if you like this book, you may also like these books" feature) so that the service will automatically become better as more users use it. I still don't know exactly how it works, but it seems to work pretty well. I like the majority of the songs suggested by Pandora and stumbled on great music by bands I never heard of before. So either it works, or I'm such a philistine that you could play any song to me and I'll like it.
In any case you should try it. Amazingly, it's even free.