The next time your boss tells you to use your head, say that you are – and point to the silver dot on your forehead. Then be sure to explain quickly that the metallic addition to your cranium is an alternative input device designed to replace your PC's mouse.

Eye Control Technologies', gizmo is called NaturalPoint TrackIR. The $99 device lets you stick a little computing power on your forehead and navigate through a digital world by moving your head.

The TrackIR hardware that gives the silver dot its capabilities sits on top of your PC monitor and is about the same size as a webcam. Its infrared transmitter and receiver track the silver dot you stick to your forehead, nose, or eyeglasses.

A tiny camera inside the hardware tracks the dot, letting you take control of your mouse pointer by moving your head. TrackIR ships with 60 reusable dots so you don't have to leave one on your head all night.

Originally, Eye Control's target customers were computer users with physical disabilities. But, thanks to a dramatic fall in the cost of the hardware, the company is now trying to broaden the market for its technology and hopes to appeal to gamers, notebook users and those with repetitive strain injuries.

We tested a preproduction model of the TrackIR and found a few glitches. For example, the TrackIR depends on infrared rays that are sensitive to light. When the sun shone directly into the office, the pointer moved erratically.

Another problem cropped up when trying to use TrackIR to play popular shoot-em-up Soldier of Fortune - the pointer tended to lose track of the centre of the monitor. Needless to say, it was soon game over.