iOS (a href="http://lifehacker.com/5771943/the-always-up+to+date-guide-to-jailbreaking-your-iphone-ipod-touch-and-ipad-[ios-511]">Jailbroken): While you can easily lock out all your content on your iPhone with a passcode, that doesn't really help when you need to hand over your phone to a friend to use it quickly. FaBActivator is a jailbreak app that gives you precise controls over what's available on your iPhone when you activate it. More »