Here is jChatBox 2.3, the JSP Chat Application (free for non-commercial sites). Server side is 100% JSP (Java Server Pages). Client side could be HTML/JavaScript, Applet, Flash or Application. System user can open and control multiples chatrooms. He/She can manage users (list, ban, kickoff), manage blacklist, generate transcripts, do backup, and apply chatrooms parameters as max users, filters ...
Chatrooms are easily customizable (skins). They can be extended by designers or programmers through the jChatBox API. Moreover jChatBox is ready for XML thanks to its XML Connector service.
An Add-Ons section is also available with tools like smiley filter, database authentication, chinese skin, LDAP authentication, Flash client.