Whether you are in college, office or on some Local Area Network, you can chat with your buddy right from your desktop.
Network Messenger is a tool that can enable you to chat in a client installed on your PC with your friend sitting on some other computer but on the same LAN. There are many tools for this purpose but what I personally use are the following tools that are purely based on the Peer to Peer connection.
The tool is very easy to use and looks exactly like the MSN messenger. No need to install, just run it and enter the IP address of your friend and you are done.
2. Lan Talk
This tool has also impressed me and is worth trying.
Both the tools can share files and has no relation with the network so you can use them secretly as well (Network Admin will have no idea of it).