There is something which is quite cheap to manufacture, and easy to integrate into ANY game concept... though, it isn't directly a controller, but just a different display-method.... its called "Head Tracking".
I actually tested this concept in a rather high-profile Wii game last year (edit: no, we didn't ship with it). Short answer: It doesn't work in most game concepts.
First problem: Requires calibration based upon the screen size and placement relative to the head tracking camera. (The Wii remote, for the Wii). This calibration needs to be pretty precise and is not easy to perform. I'm not immediately certain of how one would make it so that Average Joe Consumer could do it, though I'm sure that someone smarter than me could figure out a cost-effective and reliable method. Regardless, getting the calibration wrong severely damages the effect, and could easily cause nausea for the player if they played with incorrect calibration. (edit: getting the calibration for my own setup was by far the most time-consuming part of integrating head-tracking into our game)
Second problem: Stuff on most modern video game consoles currently runs double or triple-buffered, at 30fps. This means that between any movement of your head and the compensating motion of the screen image, there is (on average) about 90 milliseconds of lag; this lag is enough to be extremely noticeable even on small screens, and can even provoke nausea when viewing on large screens, even if the system has been properly calibrated.
Third problem: The head-tracking approach that everyone talks about (including the video linked above) simulates a 3D view of objects sitting on the other side of a window, with the screen being that window. With the size of characters on the screen in video games, this means that those objects must either act as though either they are extremely far away from the window (causes major problems with other objects (walls, trees, etc) getting in the way of the view, and slight movements of your head can change the angle of view through the window enough that you can no longer see your characters at all), or else your characters appear to be miniature people, only an inch or two tall, standing just inside your television. Neither of these is usually really want you want in a dramatic action game.
Fourth problem: The math only works on flat-screen televisions. Old-style CRTs with rounded or cylindrical tubes would not be able to replicate this effect.
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