"Speedometer" app is a free Android application that uses your phone gps to calculate the speed at witch you are going.
The app it's composed by three screens:
1)The speedometer screen (it shows current speed, battery level and battery temperature)
2)The graph screen (It shows a graph of the speed)
3)The mist screen (It shows a map with a compass, the camera, current inclination and roll, and finally a text which shows the current speed in "km/h")