Android: If you want to let someone read or watch something on your phone, but don't want them snooping around, Touch Lock can make sure they can't do anything by locking the touch screen.
The app puts a continuous notification in your shade. Simply tap the notification to enable the lock. Then, whenever you're ready to use your phone again, double-tap the barely-visible Touch Lock icon to turn your touch screen back on. Touch Lock isn't the most secure thing in the world and it's relatively to unlock, so you probably won't use this to keep out an adult who wants to force their way in. However, for keeping children from getting into apps they shouldn't be in, this is a handy tool.