I don't know just how heavy this would be on the server.
You might have noticed the Meebo chat client on the Main page. It's not quite what I had in mind, but it's a start. Currently, it only works if I'm logged into my Meebo account in another browser window. Then, you'll see me as "online". You can do a similar thing by creating your own embedded Meebo client and pasting it in a widget box on your RMC page. That way, if you're logged into Meebo (again, in a separate window), people that visit your RMC page can chat with you.