I found this mesmerising video by Joon Moon called Augmented Shadow. This was a design experiment that produced an artificial shadow effect through the use of tangible objects on a displayable tabletop interface.
The goals is to offer a new type of user-experience, with the project playing on the fact that shadows present distorted silhouettes depending on the light. Shadows display below the objects according to the physics of the real world, however, the shadows themselves transform the objects into houses, occupied by shadow creatures. By moving the blocks around the table the user sets off series of reactions within this new fantasy ecosystem.
A cool way in which the user is submitted to a real and virtual environment simultaneously. Check it out below, an interesting video to say the least.