So, when I'm signed on to Facebook and go over to Pandora (where I don't have an account and which I don't use that much), it immediately starts playing
To Catch a Predator by Insane Clown Posse.
I imagine this must be because Insane Clown Posse is talked about among my Facebook friends about 10x more than any other band.
For your FYI:
http://w2.eff.org/deeplinks/2010/04/how-opt-out-facebook-s-instant-personalization/