Lets go Old School...
Okay on mainframes.. some that I have had the displeasure of playing with there is / was a cool tool that you could use to correct a users mistakes or back them out of a hung session etc.
The command was shadow (user)
You would take over there terminal and be able to do anything as if you where at the terminal.
I can't find jack on this. I mainly would like to use this to screw with a friend of mine but to also have it in case of an intrusion. It would be great to sit there and watch what they do maybe hit backspace or ctrl c every now and then just for giggles.