This inclinometer, based on a 3 axis accelerometer, gives me the pitch and bank angle relative to acceleration vector (i.e. at rest, local gravity). I’ll combine this with the electronic compass to compensate for inclination, and will have heading, pitch and bank angles…

Stick this on your hat, and the information on head position can control your viewpoint in a computer game, or some servos aiming a camera on a radio controlled car or plane. In both cases, I’ll need to output thru a joystick or a radio-control transmitter, with a few digital potentiometers. I have a couple from Analog Devices but they are SMD, hard to prototype with. I could also use an LED plus a light-sensor, or a regular potentiometer plus a stepper motor, all of which I have… I’ll probably try them all.