We have a 'Shoutbox' over on dirtyradio...
http://dirtyradio.org/listen
I suppose its more like a sleeker version of a chat room, but it allows people to shout out and say what they think about whats playing etc.. People dont have serious conversations about music on it though.
For me, chat rooms (and forums) became too 'geeky' and were left behind when internet came to the masses. Social networks (in particular Facebook) seem to be a much more intergrated solution for people to stay in touch, chat live to an audience and share their life.
Mike