Because batteries have a limited shelf life, that flashlight you've been saving for an emergency might not actually work when you need it to. So instead of stocking up on candles, grab a couple of these tiny emergency lights from Eton that simply need you to add water to keep them lit for three full days.

The $10 Blackout Buddy H2O's shelf-stable magnesium-oxide battery remains inert until water kickstarts the chemical reaction that provides electricity to the three white LED bulbs. Since the LEDs don't produce heat the Blackout Buddy's safer to use than candles, and the housing is completely waterproof so it will keep glowing no matter what emergency you're dealing with. [Eton via Gizmag]