I once discovered a registry hack in WinNT which allows you to re-map keyboard keys. For April Fools day, I swapped a colleague's "N" & "M" keys in the registry, then popped out the physical keys on his keyboard and swapped them round. Being a touch-typer, he kept typing the wrong keys, but when he looked at the keyboard it looked like the keys were correct. He thought he was going dyslexic.