This homemade security system doesn't waste time with keys. Instead, it allows admittance only to those who know the proper code as entered on an NES controller.
Yes, knowing the Konami code just got useful again. The Arduino-based homebrew security system ejects a CD tray when you enter the proper sequence, which either unlocks or locks the deadbolt. If you enter the wrong code, you'll hear that elephant noise from Dhalsim's stage in Street Fighter 2 and you'll also get your picture snapped for further investigation. You'll also get your picture snapped if you merely knock on the door without trying the controller because really, who wouldn't at least fiddle with the controller?[Instructables via Crunchgear]