The net send command is a useful Windows command to post a quick message to any PC connected to your LAN.
Like the Google Talk badge, site visitors can send your private messages via the Yahoo! Messenger Pingbox chat box without using their own IM client.
With the new Google Talk Chat Badge, you can interact with people who do not have a Google account. You need to be a Google Talk user to create a badge, and you need to be online in Google Talk to enable people to chat with you.