Shoutbox

Nice idea, but I can't think of how you could do it. The list of what you are listening to is sent via the server to all of your contacts, so there's no way you can get it to be selective.
However yes, this would be a good idea, there's a few smartarses who when I'm listening to some stuff may enjoy mocking the fact that I sometimes listen to TV Tunes, if I hear a good one