MSG

MSG is a program for sending NetBIOS (more commonly known as "Net Send") messages from a graphical interface.

In addition to being a lot easier to use than the command-line based "Net Send" in Windows, MSG allows you to do a lot of things that "Net Send" can't. Features include the ability to search your workgroup or domain for available computers, the ability to send to entire workgroups or domains (or to any combination of computers, workgroups, or domains), the ability to specify the "From" field of the message, and the ability to easily browse file and printer shares on local computers, all from within an easy to use interface. MSG is a very useful tool for dispensing messages quickly and selectively on your LAN.
If you install the optional MSGProxyService component on a web server running IIS, you can also send to computers on the workgroups / domains local to that web server from a remote location. So, for instance, you can install the MSGProxyService on a web server on your company network and then have all of the same capabilities from the MSG client at home that you would have if you were on the company network locally. Security features of the MSG client communication to the MSGProxyService include password protection, message integrity verification, and replay attack prevention.
MSG is made available as FREEWARE. It contains no virii, adware, spyware, back doors, or trojans.