MiniChat is a Java applet client that can be seen on the bottom of this webpage. MiniChat also consists of a Java console application server. The server probably isn't running right now, so the applet won't connect. But if it was, the applet would automatically connect to the host, and you can chat with anyone who is also on this webpage.
Some screen shots of the program in action: ScreenShots.html
The applet is hardcoded to connect to port 6789, so you need to pass 6789 as a command line parameter to MCS when you run it. All source code on this page is copyright by Michael Wales. Do not use or reproduce code without my consent.