I don’t know if it’s technically feasible but perhaps using the data from accelerometers on the iPhone and with the help of something to stitch the iPhone to your hand a 3D joystick could be made. I mean something to control an application or a game on your Mac like you do with a Wiimote… It comes to mind that if it could be made by mean only of accelerometers the guys at Nintendo would have not used the IR sensors together with the accelerometers…. Just another silly idea perhaps…