This Bulb Flashlight will put you at ease of worrying if there's batteries in your flashlight. The reason? It's always charged.

At $45 it's expensive even for LED bulbs. The reason for it? It's got a built in rechargeable battery that's always charging and always ready. You'll need to use it as a regular bulb in a lamp where the equivalent of 40W of incandescent light is concerned.

When there's a blackout, unscrew the bulb and extend the handle and you've got three hours of emergency light at your disposal. Not bad at all. [MoMA Store via The Gadgeteer]