I'm working on a game platform that turns your iPhone, android or iPad into a steering wheel, for racing games (like need for speed and dirt 3) and flight simulators for example. I'd love to figure out smart ways to figure out whether gamers would like something like this. I originally asked this question over on the gaming SE and it was for getflypad.com. A lot of the tech is built and most of it is doable - the question here is how to test demand and know whether gamers actually want this.