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.
MyChat - Secure instant messenger for any network
Bopup IM Suite - Organize secure messaging system and communicate instantly via self-hosted IM server.
BORGChat - BORGChat is a LAN messaging software program.
BeeBEEP - You can message and share files inside your intranet without a server.
BigAnt Office LAN Messenger - BigAnt Office LAN Messenger offers rich features for secure and stable business communication.