LAN Messenger - LAN Messenger is a decentralized UDP IM-style chat client which supports usernames...
Anologue - Disposable online chat.
MyChat - Secure instant messenger for any network
EchoWaves - Opensource Social Group Chat written in Ruby On Rails
BORGChat - BORGChat is a LAN messaging software program.
JabbR - A chat application built with ASP.NET and SignalR.