[Rory Hyde] and [Scott Mitchell] are exploring several projects that add more information to public spaces. The first is the Spoke-o-dometer a persistence of vision device that can display bicycle speed and distance traveled. To develop the device, they first bought a few POV kits to test out. They decided to build their version using an Arduino. Once they had the display proof of concept working, they added a hall effect sensor like the SpokePOV so they could determine speed and orient the display. Check out their project site for plenty of example code and development details.