The Phantom Keystroker is the ideal instrument for practical jokes, possibly at the office. Once attached to a USB port, the Keystroker will send random mouse and keyboard commands (like CAPS and more…) and random text. It is somewhat configurable with three switches, and you can even set a timer to activate it.

The Phantom Keystroker is not really discrete and would likely work better on desktop machines , but an ultimate version should be pluggable in an internal USB port, directly on the motherboard.

ThinkGeek