Power Pad
Even if the Power Pad didn't always work, it was one of the coolest additions to your original NES setup. A bond was formed across all gamers that used the pad to cheat in Track & Field. No one actually ran that one out, it was a collection of gamers beating the system by pounding on the mat with their fists. For as underdeveloped as the Power Pad was, it pushed the peripheral medium forward, paving way for current games like Dance Dance Revolution.