The original HoloToy was a fun little app that could simulate 3D in pictures by tracking the accelerometer movement of your phone. Tilt the phone to the right and your image looks like you are viewing it from the right side. The effect is pretty darn cool, especially when you really get into making your own pictures into holograms.
HoloToy's newest update, version 1.07, takes the concept and adds a sprinkle of iPhone 4 awesomeness. Instead of just being able to change your viewing angle with the accelerometer, HoloToy now uses your front facing camera to change the image angle depending on where your head is looking. It almost gives you the feeling that you can peer around images to see what's behind them.
HoloToy's creator Ben Hopkins had this to say. "Since release it's been great watching peoples reactions to HoloToy. As soon as I heard the iPhone 4 had a front facing camera I knew that this would be the next big HoloToy feature. Moving the device and seeing the 3D scenes move as expected is surprising, moving your head and seeing the 3D scenes move as expected is magical!".
While Ben's comment ("it's been great watching peoples reactions") may lead me to believe that he is personally watching me through my camera, his statement about the technology being magical rings true. The face tracking isn't perfect, but if someone could perfect this we could finally see the end to those silly looking 3D glasses.