After spotting this tip on Lifehacker and sharing it with friends, we discussed ad nauseam different strange and contrived situations you'd have to be trapped in to make use of it. But in case you do ever find yourself as a spy involved in an international scandal where your laptop is seized by the feds in an unannounced house raid where they've also managed to break and/or lose the part of your charger that plugs into the wall socket—whew!—then it might just come in handy.
Any device that grabs a charge from being plugged into a USB port—that includes your iPhone—can get it's juice from mostly any powered up (it has to be "on") piece of tech with a USB connection.
If the spy scenario above does ever happen to you, you won't go uncharged. But there's other ways to use this tip to your advantage.
Some people find themselves leaving their video game consoles, like the PS3, on for hours unattended while their controllers juice up. Instead, try plugging them in to the port on your TV while you watch Top Chef.