I originally had one, but it was a bit resource intensive. I was considering putting it back in when I do my site redo and move some stuff to Node.js. But I'm not sure people would use it, given the nature of the site.
Keleth you should look at doing it with WebSockets. It's easy in Node, or even Go, and it's not resource intensive. The chat server could just sit there idle till called upon.
As mentioned above RustyInPieces, I'm planning on adding some Node, specifically for websockets. I was looking at a chat system, but donno how much it'll be used; I wanna avoid time on features people aren't gonna make use of when there are so many they probably will.
Originally, I had in a chat system per game, where the GM would start a session, people could chat, and the GM could end the session, and the transcript of the chat would be logged into a subforum automatically generated in the main game forum.
I've never used chat functionality on a forum site. I'm already connected with friends on G+, Twitter, etc. If I want to chat real time with someone, I use one of those.