Well, there's this website that has something on it called Pandora
Fairly simple concept, you type in a Song Name or an Artist Name. It will run through a database of music and pull music that follows the same patterns and styles of that song or artist from different bands.
Since I'm not very good with explaining things, you'll just have to check it out for yourself.
It's a great way to find new bands, and even hear stuff from current bands you're listening to.
Just a note that sometimes it's innacurate, sometimes it plays crap, and sometimes you wonder what the hell it's trying to set you up with. But trust me. More often than not, it'll play some good music for you.