Write or ideally adapt existing free software to enable use of the Nintendo wii rvl-cnt-01 remote control with 2 or more infra-red LED-s for real time head tracking.
The wii controller would be next to the PC screen and only the user's headr would move to change perspectives of the 3d representation..
Provide a generalized "driver" and 1 or 2 simple sample documented head tracking controlled 3d applications in PHP as well as Javacript using the driver.
Reference: "Head Tracking for Desktop VR Displays using the Wii Remote" in [url removed, login to view]
and on the Web various forums/articles/software such as Wiimote.
System should work in Windows 7 and ideally also Windows 8 and earlier systems.
You should have your own wii controller ad he necessary infra-red lights.