Now ain't that a coinkydinky. I read the new Computeractive which has an article about Pandora, then log in and find a thread aboiut Pandora.

There are also a few other sites that do the same, but with varying degress of accuracy. One or two, like Pandora, matched songs based on a computer analysis, whilst others match them based on what other users like.

www.gnoosic.com
www.musicmobs.com
www.last.fm

I've just tried Pandora, and they don't have Arctic Monkeys as an artist.