The AMPware Power Generating iPhone Case is an iPhone 6/6s battery pack that could easily save a deal or, in extreme circumstances, a life. Or, it could simply save you having to queue and pay for a charge at an outdoor event such as a festival. Its maker also claims that it is the first hand-cranked dynamo-powered phone case, and I can find no evidence that it isn’t.
It is far more than a gimmick in my view. I’ve found that a couple of minutes of energetic turning can keep you in contact with the world for a couple of short calls, while 10 minutes gives you a couple of hours of voice and data use. The AMPware was developed in response to Hurricane Katrina, and is said by the manufacturer to be over 20 times more efficient than solar-powered alternatives. It’s not absurdly cumbersome, either, and weighs a reasonable 110g.
Even if you’d feel a bit of a twit cranking away at your phone in some remote spot where you were doing business, you may well be the only twit able to phone the office, so I’d get over any embarrassment.