Google's Project Tango

Tango lets you see more of your world. Just hold up your phone, and watch as virtual objects and information appear on top of your surroundings. So no matter where you are, there's always a richer, deeper experience to engage with, explore and enjoy. You'll see.  Measure your surroundings with 3D tools, then re-imagine them with virtual furniture, appliances and more.  Bring virtual objects into your world—from toys to planets to pets—and play with them like they're actually there.