For iOS 7.0 - 8.4
Compatible with iPhones, iPads, and iPod Touches
Unlock your iDevice with a picture! Picture Passcode allows you to set a picture to replace (or to use alongside) your standard passcode. Using Picture Passcode is as simple as 1) choosing a picture and 2) tapping anywhere on the picture as many times you wish. You can then unlock your device with your picture and tap pattern.
Video demonstration by Jeff Benjamin (starts at 8 minutes, 52 seconds):
See larger Screenshots below..