The X-Gyro 500 is a simple single axis head tracking system that can be used to track head movement to for controlling an on board camera in an FPV system. Since today it is available from Hobbyking for US$ 37.44
Specifications:
Voltage: 8~12v
Weight: 20g
Range: +/- 90degree
Compatible Transmitters:
FUTABA: (FF-7, FF-8, FF-9, T9Z, T12MZ, T14MZ)
Graupner: (MC20, MC24, MX22)
Multiplex transmitter: (Royal Evo, Cockpit SX, mc4000)
JR and other transmitters without programmable channel: (9303, 9X)
The user manual can be downloaded here
Link to product page: http://hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=14628&aff=5361
Comments
Looks like this can be used with any Tx if you combine it with HobbyKing's PPM mixer which sits between the RF module and the Tx "computer". Maps two new channels above 6 in the PPM signal. Need an 8ch Rx and some soldering skills though. I'd probably look at the 2 channel version of this head tracker. You could apply yaw by turning your head left and right and then look up and down to move the camera. All on backorder at the moment on their website.