LAN Messenger - LAN Messenger is a decentralized UDP IM-style chat client which supports usernames...
Shtuff Chat - Free Group / Team chat with persistent history.
Softros LAN messenger - LAN messenger for an internal office chat for home or business users. It does not require a server and is very easy to install and use. It supports personal chats, group chats, message brodcasting, files transfer and remote desktop access.
Meet in Chat - Meet new people. Have fun sharing photos.
MyChat - Secure instant messenger for any network
Kandan - Open Source private chat server. Your own private Chat server in minutes, plus additional features.