LanTalk.NET Messenger 

LanTalk.NET Messenger is just great. I couldn’t find more of LAN messengers on the internet. The software is very small, less than 1MB. LanTalk.NET Messenger helps you talk to anyone on your network. LanTalk.NET uses TCP/IP and UDP protocols. So, the communication with other computers on their network is not interrupted by the server and other settings.

Read-Only and Reply-Only modes are versions of the software that can be set during installation. It can be used to prevent the workers on your company from wasting time chatting within themselves.

There is a scheduler. Its makes it very convenient to send messages at a particular time, or to give commads to your employees at a particular time.

The price is quite big for a home network. But for a company or a big network, the price can be described as small / fair.

I really like this software. I use it at my home network. It is really good. I find it very difficult to use the regular windows commands to send message over the network. It really doesn't work well. Lanatalk is good. Many more features make it a really good program.