ZooKazam (free for a limited time) is a terrific augmented reality app. You print out a target from the Zookazam website, put it on a flat surface, and point your iPhone at it. You'll see a 3D animal moving in real time. Circle the animal, and you'll see it from every angle in very smooth renderings. Change the weather to heavy rain, and rain falls out of the virtual sky. Kids and adults will both get a real thrill out of this app.
I've seen some similar apps in the past, but ZooKazam renderings are very realistic, and the shadows are consistent as you move around the object. The virtual animals aren't limited to the printed target. I watched ladybugs wander around my desk and fly in the air.