If your keyboard can do it ... You can even set a key on your macro pad to just lock your PC so no one can use it while you are not around. This is a big one for me and probably the task I ...
the Num Lock key. This switches JAnK over to 21-key macro pad mode. [Clewsy] rolled their own PCB for this and used the venerable ATMega32u4 because of its HID and USB host capabilities.