WebChat is a versatile new chat system with both Java and Windows clients. It is designed for a variety of uses, ranging from serious customer-services based operations to the more social aspects of chat.
The biggest WebChat! customer at the present time is GipsyMedia, who are using it for both technical support and as a community part of their site.
You can download the a trial version of the server and a full version of the Windows client from here.
More information about the WebChat! server.
The webchat native client provides a more powerful way of chatting on WebChat servers.