Since Joomla! updated recently, the new version of 123FlashChat Joomla module released, too!
The Joomla! Chat Module/ Joomla! Chat Extension, Introduction:

1. Integration: With the chat extension for Joomla!, you will be assisted in embedding a real-time chat room with the Joomla! database of your website integrated.

2. It can display following data in the Joomla! front page:
* The connection number of the Joomla! Chat.
* The logon user number in the Joomla! Chat room.
* The chat room number for Joomla! Chat.
* The chat users' name list in all Joomla! Chat rooms.

3. Auto-login: Once logged in Joomla!, users don't have to re-enter their username or password again to access chat.

4. 123 Flash Chat for Joomla can run on different browser in many different platform, such as Windows, Linux, Unix & Mac.

What is 123 Flash Chat Server Software?
123 Flash Chat Server Software is a feature rich and high performance Java chat server with a cool Flash chat client! It's a fast, easy and affordable way to host and manage real-time communication. 123 Flash Chat server software can integrate existing databases of forums or websites. It's fully customizable for admins and end-users.
And there are many more functions at http://www.123flashchat.com/feature.html