Here is a one for bicycle enthusiasts: A Magnetic headlamp. This clips on to your handlebars and comes with a small, yet one of the brightest handheld torch lights I've come across.
The light is a focusable LED spotlight and uses 4 AAA batteries.
The base of the light uses rare-earth magnets and can be removed while your bike is parked. Because there are both magnets in the base and the backend of the light, This can double at a worklight in the garage, shop, or around the house.