About WCF Chatroom
This sample demonstrates how easily TCP chatroom server (console application) and chat client (windows application) can be written, making use of callback contract, duplex NetTcpBinding and sessions.
Many clients can connect to chat room and chat together:

System Requirements
To run this programs on Windows XP or Windows Server 2003, Microsoft .NET Framework 3.0 Redistributable Package must be installed! On Windows Vista it just works out of the box.
Download
You can download source code (i.e. Visual Studio 2005 solution) here and use & modify it freely as you wish:
Download chat room client and service source codeLicense information
This software is provided 'as-is', without any express or implied warranty. In no event will the author be held liable for any damages arising from the use of this software.
Permission is granted to anyone to use this software for any purpose, including commercial applications.
Author
This chat software is written by Nikola Paljetak