Sam Garfield modded this NES controller into a cell phone using Nokia 3200 parts:
As the night went on and the idea evolved, I thought to myself; “Self, why not make the controller into the actual phone?” Self thought this was a great idea and we set to work. My first idea was to use an actual GSM radio and build the other electronics and antenna. I ditched the idea when I remembered my old Nokia 3200 which I had sitting around.
The Nokia 3200 was advertised as the “American Idol” phone or some such nonsense. Because it has interchangeable face plates, the case was removable. In addition, each button actually has two digits on it, so there are half as many buttons as normal. These two facts make this the perfect phone for modifying - easy to get to electronics, and less buttons = less cutting.