My local dentist used to use this as a sort of intercom system. When the hygienist was done cleaning your teeth, she would use winpopup to broadcast a message to let the dentist know that the patient was ready in exam room 6. It made cleanings at least a bit enjoyable.
At one point I was using the WTSSendMessageA API to send messages to our son. The API was called by a custom Windows service I wrote which I’d call over HTTP.
