Android: There are times when you have to mute your phone, but many of us forget to unmute it when we're done. Shush! solves that problem in the least obtrusive way possible.
Shush! activates as soon you use your phone's volume buttons to turn it down to vibrate or silent mode. At that point, you'll be presented with a dial you can use to set the duration of the silent period, how loud your phone should be when it comes back, or whether to remain silent indefinitely.
Shush! [Google Play]