If you listen to a channel, type in an artist name and it then picks singles from "similar" artists. It's pretty good at picking stuff I either like or am likely to like.
For example - type in
LFO, and it plays an LFO track
then Raxmus
then Autechre
then Quoth
There's a Firefox plugin available also...you don't need the client software.
It will also track your listenining habbits from itunes or wherever ("scrobbling") and recommend music basedon that.
I was 16 at a 6th form school organised under 18s disco that served alcohol to all of us when this was out.
How odd. Get locked up for that sort of thing now.