Chat rooms

I read different threads on this subject, about jabber, irc, IM's and what not. All it did is was leave me confused. Is it possible to run a moderated chat room that is controlled by time and number of participants on the shared server program.
How much difference is there bewteen the before mentioned programs? Isn't a chat room similar to a forum, with the exception that the screen refreshes instantly.
The reason I was asking as one of my members was asking about this subject, and it kind of makes sense to use if it is allowed. I was thinking about a teacher, moderator and a few students. Kind of virtual class room.
What ever information you can provide, I would be grateful, as even if it not allowed, I can atleast get it off my mind.:)
Silk

An IRC host/chat client is a constant process that is forbidden in DH's policy.
Jabber is an allowed program/IM service that is run, but I think this is more IM than chat?

I'm not too clear on it myself, but you could always run a PHP/Javascript chat based program. Try looking at SourceForge for PHP based solutions

I use Blab, and got the approval from DH to use it before I purchased it.

Yes, it's not free, costs about $30 US dollars...but easy to set up and well worth it. Multiple rooms, a way to make a chart that says whos online in your main index page, the ability to upload pictures..etc.

http://hot-things.net/blab.php