Mousefield by Masui, T. , Tsukada, K. and Siio, I:

a new simple and versatile input device called the MouseField, which enables users to control various information appliances easily without huge amount of cost. A MouseField consists of an ID recognizer and motion sensors that can detect an object and its movement after the object is placed on it. The system can interpret the user's action as a command to control the flow of information.

By placing and moving an object, the user can interact with the system: They provide an interesting example: