GPS Speedometer Overlay

Displays your current speed in an overlay which you can place over your navigation app when driving.
Customise size, position, colour and transparency.
Supports Kilometres per hour and Miles per hour units.
Analogue speedometer, or digital speed readout with average speed.
Tap overlay to reset the average speed (great for average speed cameras on the motorway).
Will show over your navigation even if your device is locked.

Instructions:
To open the settings, long press in the bottom left corner.
To close the app press the launch icon again or long press the top right corner.
Long press and then drag the top left corner to move the overlay and the bottom right corner to resize it.

Speed Overlay is currently being actively developed. If you encounter a problem, please consider using the Email Developer link below rather than just leaving a low rating, that way I can attempt to resolve the problem for you ASAP.

Caveats:
The average speed calculation is currently very simple. I'm looking at improved algorithms. Currently the options are.
Average of Doppler instantaneous velocities. Fine if your GPS chip provides very regular updates, and the more accurate Distance Over Time, which is prone to some variation of distance due to GPS jitter. Both will be more accurate in motorway driving than city driving - so just fine for keeping an eye on those annoying average speed camera zones on the motorway.