Have you ever wanted to look in your own ear? Or at the nape of your neck? Or behind furniture? If you own an iPhone 4S and an Apple TV, you can wirelessly beam the picture from your camera to your large screen TV.
Just enable AirPlay. Double-click the Home button, swipe to the right twice, select your Apple TV as your AirPlay destination and enable Mirroring.
Then, click Home and run the camera app. You'll be able to see what the camera sees because its preview mirrors to your home TV, even when your arm is stuck behind a dresser. You can also point the iPhone camera (front or back) at your ear, your nose, or your back -- letting you see through your phone by watching your TV.
You may want to use a flashlight along with your phone as you explore darker parts of your house, like under your couch when looking for spare change or that missing remote.
Update: TUAW reader Sam W suggests mounting the iPhone onto a remote controlled truck for full-house surveillance.