AJAX, with all its constant polling, is a pretty weak approach to chat. This visual chatroom uses javascript, sockets, and dhtml to connect live to a server. A flash to javascript tool called AFLAX (from the Aptana people) handles the socket connection. DHTML allows you to move your avatar around and chat in a virtual "room," while a perl-based server handles the backend socket server stuff. This is a good example of how to wire together users live over the internet, without resorting to flash or java.