A free program for Android, by We Organic.

GPS Speedometer is a useful GPS app that can calculate your speed in kilometers per hour (km/h) or miles per hour (mi/h). You can also track the distance of your trip in kilometers or miles. It is a simple app that calculates the speed of your vehicle and displays it on a digital HUD. It is useful for calculating the speed of a car, bike, truck, etc. You can also use it to calculate the speed of your bicycle, motorcycle, or boat. 

This app is designed to work on Android smartphones and tablets. You will need to download the app from Google Play.