Nearly Instant Message
From Just Solve the File Format Problem
Nearly Instant Message was a very popular way to leave comments for a freesite. It used KSK to transfer messages via web interface (known as Fred).
The key used for the message would be KSK@somestring-N where N are the sequential numbers. Each key can be used only once.
NIMs were a very archaic way to send a message. First one needed to check if the specific number was still empty by attempting to check it. If the error was received, then it was possible to insert into that slot.