PHPOpenChat
PHPOpenChat – The php free chat-server-software for live chat-room or module
PHPOpenChat PHP is a high-performance software-based instant messaging server for a chat-room or module on each site based on PHP. The first version was developed for a live-chat-subproject of the main portal training German (DBS) called "SchulWeb. The PHPOpenChat had to handle a lot of people, talking about 100-150 competitors, most of the firewall and in front of old computers. Based on this experience, we have developed the version 3 of our free chat-server completely new from scratch.
Right now you can integrate the chat software with PostNuke, phpBB, yabbse, etc. as a module.