I'm surprised no one else mentioned it, but the Find My IPhone app is a great one. Lets you remotely lock or remotely wipe all your info clean from your iPhone. It will also help you find your phone if lost, you can track it down to within feet, to catch the thief who stole it or find it in the truck between the seats! The app also lets you send a ping that makes your phone ring... Even if it's on mute... Very nice feature when your kid hides your phone under the couch!!
