ShakeLight

It is the zombie apocalypse. You are in a dark building scrounging for food. There hasn't been any electricity for days, and you can't see a thing. All you have is your smartphone to help you light the way, but your battery is low. What do you do?

Well, if you downloaded ShakeLight back when there was still internet, you can shake your phone to help recharge the battery by converting kinetic energy into electrical juice! Tons of flashlights have this ability, so why not your smartphone? You can even feel the damped massed move up and down, providing you the much needed energy to help you find those nourishing Twinkies while you mow down wave after wave of zombies.

Note: This app is for fun, and will not actually charge your phone. However, it will still be useful for finding Twinkies during the zombie apocalypse. Shake, light, survive!