A full version app for iPhone, by Unicom TOV.

Speedbox is a free digital head-up display (HUD) for use in a vehicle. It is designed for cyclists, runners, drivers, pilots, sailors, swimmers, surfers, windsurfers, paragliders, kiteboarders, skateboarders, snowboarders, snowshoers, and other forms of motorized transportation.

With Speedbox, you can use your smartphone or tablet as a screen for a GPS map of the road, and it will display the current speed in a digital head-up display. Speedbox is designed to be simple, and to provide the user with a quick and easy way to view the speed limit of the road. The user can set the display to switch between normal viewing and HUD mode.