iPhone app developers never cease to amaze me, re-inventing not only the software, but also the hardware itself, like the iPhone air blower app. Or Pocket Heat, which can turn your iPhone into a real heater. But how?
Easy: The app puts your iPhone at 100 per cent of its power processing capacity in all its systems, which makes the components overheat. There's another application like this, called iHandWarmer, but Pocket Heater wins on design principle alone.