Still using your smartphone's power button? How 2014.
Gravity Screen (Android) is a free app that relies on your phone's accelerometers and other sensors to give you a motion-powered alternative to the power button.
Put simply, if you put your phone down on a flat surface, Gravity Screen turns off the screen. Pick up the phone and the screen springs to life. Kind of ingenious, no?
The app can also sense if you've put your phone in your pocket and, again, deactivates the screen (a good way to prevent inadvertent pocket-dialing). And if your handset has a proximity sensor, you can simply wave a hand over it when it's lying on a table and the screen will spring to life. (There's at least one other app, Wave Unlock, that offers similar functionality.)
I tested Gravity Screen with a OnePlus One, and it worked exactly as advertised -- which is to say, extremely well. Your mileage may vary, of course, because of the differences in Android hardware and the Android OS.
To get started, you simply install the app, run it, then tap Activate. From there you can modify any number of settings, but your best bet is to fiddle with the defaults and make sure things work.
For example, with your phone on, simply set it down on a table or other flat surface. Within a second or two, the screen should go dark. Then pick it up. Bam: screen on.
That's what happened on the One, and the wave-unlock featured worked perfectly as well: I simply waved my hand about an inch from the screen and it woke right up.
This sounds like such a tiny amenity, but it also makes a ton of sense. Actually having to reach for the power button when your phone is tableside...it's a hassle! And not having to remember to hit that button before parking the phone in your pocket -- huge plus.
If you plumb the Gravity Screen settings, you'll see plenty of ways to tweak the various sensors (pocket, proximity, motion, table), plus options for the power button, headphone jack and so on. You can also disable the lock screen if you'd rather save yet another step in getting right to your apps.
Gravity Screen is a great little app, one I highly recommend for Android users.