Smart Screen Off is free and works as advertised. If you wish your phone’s display would turn off as soon as you put it in your pocket, or put it down on a table without having to rely on the screen timer to do the job for you, this app can help. Keep in mind that it just cuts power to the screen — it doesn’t lock your device. A number of people in the forum note that the app is especially useful for those with flip-style cases, or if you’re exercising while listening to music and don’t want to unlock your phone every time you want to change songs. Smart Screen Off supports any version of Android, but it requires your phone have a proximity sensor to work (it probably already does). You can snag it at the Android Market.