Thanks to the LED technology, now you can get more lumens per Watt than incandescent light bulbs. LEDs can be as small as 2 mm2. Due to their high efficiency, lower cost and longer life, these can be attached to any device.
Wrist Watch Torch Light is a Portable LED wristwatch that is equipped with a compass and a flashlight for outdoor enthusiasts. It is somewhat bulky but a great resource or running at night or camping.
You can own one for just under $15.