Well, if you've used Pandora at all, it's like Pandora for your iTunes library. It'll take a song, and (theoretically) identify a bunch of other songs you own that are similar to that song. It'll also give you a bunch of suggestions for songs that are available in the store similar to that song.

If that makes sense.

So, I wound up with an acoustic/light rock-ish playlist of PURE AWESOME.