iOS Pick: ElfYourself
Leo Laporte's app cap on iOS Today 322 is ElfYourself. You'll take a picture using your device or by finding one in your camera roll. Then you line up the face onto elves, and choose a dance theme.
The app generates a custom video using the elves with your friend's faces on them, making them dance to a holiday song. Then you can share that video in an email or on Facebook.