This video gives an introduction to the USB Rubber Ducky from the guys over at Hak5. The Rubber Ducky is a device that looks like a thumb drive but masquarades as a keyboard and can type keystrokes on the machine it is plugged into. The USB Rubber Ducky can also be formatted to work as a USB thumb drive in addition to a keyboard. It is an interesting attack vector as there is no simple way to block this type of attack.