LAN Messenger - LAN Messenger is a decentralized UDP IM-style chat client which supports usernames...
MyChat - Secure instant messenger for any network
BORGChat - BORGChat is a LAN messaging software program.
Bopup IM Suite - Organize secure messaging system and communicate instantly via self-hosted IM server.
RealPopup.it - A network messaging application that's feature-rich yet easy-to-use and won't cost you a fortune, RealPopup LAN chat offers fast, stable messaging across your local network. No application server required, just install on your PC and start messaging!
BigAnt Office LAN Messenger - BigAnt Office LAN Messenger offers rich features for secure and stable business communication.