You know you're a nerd if you enter the Konami code to unlock your door

This Arduino-based homebrew security solution takes the input from an NES controller (mounted, I suppose, anywhere you like) and passes it to a little string detector. If you enter the right sequence (Shoryuken!), it ejects or recalls a CD tray, which locks or unlocks the deadbolt respectively (reminds me of this great IT admin story).

If you enter the wrong code (tatsumaki senpukyakuu) it makes the elephant noise from Dhalsim’s stage — very irritating. It also takes a picture with the door-mounted webcam, so you know who’s messing with your controller. If they don’t think to try the controller and knock, it also takes a picture of them, because only suspicious types wouldn’t at least give it a shot.