Here's a robot video that I found interesting:
ELEKIT Japan exhibited the Switch flip sign - a really simple yet effective robot sign project kit. The sign incorporates a sensor with a linked flip mechanism to switch displays back and forth when the sensor is triggered. Customers can use their own custom graphics to create a unique interactive sign.
The only drawback is the price. As simple as the concept is, including the minimalist cardboard frame, it's hard to understand how they justify a street price of around USD$40.