NetChat is a peer-to-peer local network instant messaging and communications system for Windows which does not require a server to be running for use. It allows you to chat in real-time with other users on a secure and private local network connection.
LanToucher Network Chat 1.2.11
Simple chat messenger for office and home
Secure Network Chat 2.10.15
Secure text chat
Easy to set up live support chat tool
A full-featured ASP.NET chat
TCP/IP Winsock Toolkit for Windows Developers