The list of NES case- and controller-mods we've seen covers just about everything imaginable, but Joe from the modder site Proto Dojo goes one better - making a USB drive unlockable by the Konami Code.
As Joe and everyone who's seen this point out, that's rather like picking 1234 for your ATM PIN. Because the first thing anyone would do with an idle, disconnected NES controller is punch in the Konami Code out of boredom. Joe shows how it works, and so I assume the code can be changed up. But whatever its utility, it's damn cool and a triumph of mod ingenuity.