Reminds you your iPhone is in silent mode
Silent is a simple utility to help you to remember that your iPhone is in 'silent mode'.
It is easy to forget that the little ringer/silent switch on the side is switched down, as there is no persistent indicator on the iPhone's screen that lets you know. When set to silent, incoming calls or messages won't make a sound.
The result: missed calls and messages when you should have heard them!
When you switch the silent switch, also touch the Silent app and it will set its icon badge to '222' (reminiscent of 'zzz') so that you'll notice it is in silent mode on the iPhone's springboard
Also, you can have the app schedule a reminder notification which is pushed to you at a later time (you choose the length of time), if you haven't switched out of silent mode in the meantime. The push message could also vibrate your phone depending upon your ringer/silent settings.
When switching back out of silent mode, just run the app again to clear the '222' reminder and cancel any pending push notification.
Finally, you can configure silent to exit immediately when it starts, saving you from pressing the home button or tapping the screen to set the reminder quickly.