ChattyWays, a .NET Chat Application is actually on use here at XMLPitstop.com. To see it in action, you can click on the Chat link in the left panel. Feel free to chat here as well as to download it and set it up on your own website. I must confess that I had as much fun adding the emoticons and IMVironments than writing the application itself.
Please note that I have a seperate section in the Discussion Boards just for ChattyWays questions. If you should have any questions about running or setting up ChattyWays, please do not hesitate to post a question.