This is really cool, kind of expensive though. Its a 9Volt LED with a tilt switch to turn itself off and on. Fits directly over a 9volt battery and attaches itself to the terminals. This should be an easy thing for someone to remake.
Very cute, very clever and very practical, the ingenious 9 Volts LED light fits directly on the terminals of a simple 9V battery. A clever little tilt switch mechanism turns the light on when standing up and then off again when on its side. Available in either red or blue, add a subtle tint of color to your indoor or outdoor lighting… but, if you plan to color-coordinate, you may want to double-check, as both models, when in the off position, start out an identical white.
http://www.gnr8.biz/product_info.php?products_id=707
