I'm sure there is a module out there that offers it - once more people join and come aboard, I'll check it out. There are about 10 modules I still have to install to get this place up to my own personal standards.
Then I gotta recruit some moderators who don't have a problem with the "ban" button.
I was just about to get on and post the same thing. If they don't have one that could be incorporated with the forums, we could just hold a separate chat through AIM or Yahoo or another messaging client. Great idea though! It'd be great if we could get one through the forums.