There is an older iMac computer at the Hackspace in Manchester that is a sort of communal jukebox with lots of diverse song types. One of the members there hacked a minimus board into a joke panic button and rigged it so that when anyone hits the button the current track playing is skipped.
Maker blog thinkl33t reports that the original button was opened up and the contacts from the switch were applied to the minimum board. An application for the AVR language was written that sends the keystroke when the switch is hit. Finally a hole was cut in the side of the button to allow a corded USB connection to the computer.
If you want to replicate this project, visit the source link below for photos, step-by-step instructions and the AVR source code.
What other uses can you think for a button that sends a keystroke command? If you're in a high-crime area, you can always rig it to alert the authorities when pushed. Share your ideas in the comments below.