this must already exist

Stupid hack idea:  a local script that pulls currently playing from one of your friends last.fm profiles and updates your IM status with what they're listening to.  Have it update in real time for that creepy simulcast effect ("OMIGOD, we're listening to the same stuff"), or have it pull from the friends' playlist archive at random to leech off their coolness ("yeah, I'm into <cool hip band> too") or fake a shared interest for other purposes ("I can't believe we're both into <cool hip band>; we should get together some time").