There are a lot of hidden features on your phone that allow you to do a bunch of cool and interesting things that you otherwise wouldn't have known about. One of my favorites is one that I use so often that I completely forgot it wasn't more widely known. Some phones even have the gesture switched on by default, though that isn't helpful if you don't know about it.
I am, of course, talking about the ability to launch the camera by double-tapping the power button. A feature that is so convenient, I can't believe Apple hasn't stolen it for the best iPhones yet.
