The Nightstar flashlight from Applied Innovative Technologies Inc., Ft. Lupton, Colo. (nightstar1.com ), eliminates the problem of old or missing batteries. It doesn't need any. Instead, the user shakes it back and forth, sending a rare-earth magnet back and forth through a coil of copper wire. The electricity generated by this action is stored in a heavy-duty capacitor and, when the light is switched on, powers a white-light LED. Thirty seconds of shaking provides up to 20 min of light, enough to illuminate a 12-ft circle from 50 ft away. The housing is watertight polycarbonate and strong enough to keep the light operational down to 2,210 ft below water, the equivalent of 960 psi. The acrylic lens, which focuses the LED's output into a uniform-intensity beam, is shaped to resist pressure and withstand shocks. Repulsor magnets are set up with their poles opposite to charging magnet's, preventing the charging magnet from slamming into the ends of the housing. The capacitor, unlike batteries, works in hot and cold environments, can be recharged several hundred thousand times, and will not corrode. The power switch glows in the dark after short exposure to light, is reliable (rated at over 1 million cycles), and nonsparking. The last point means the light can be safely used in explosive atmospheres. And if you're lost in the woods, the flashlight, which costs about $50, will point north when suspended.