Instructables user Jason1820 rewired his Game Boy Advance to accept controller inputs from a Dance Dance Revolution controller, creating the weirdest way to play Pac-Man since the board game. The resulting monstrosity is neither a console nor a handheld, and is really unsuitable for anything but being insane. Thus, we love it.
This guy rewired the circuitry on his GBA to take an external controller, and one that was meant for another system at that. Then he wrote up detailed instructions on how to do it yourself, and added pictures. Meanwhile we couldn't muster the wherewithal to make dinner today, and we'd barely know how to turn on the GBA without the instruction manual.