I've wrote a very basic software that helps you to not go faster than you should. In this first release you have only three buttons to select a maximum speed, when you go faster, it warns you with a red background. I have a long TODO, please be patients.
You can download it here: http://garage.maemo.org/frs/?group_id=1017
Many TODO in my mind:
- Support miles per hour
- Sound alarm
- Configurable buttons (for different speeds)
- Make it more beautiful (bigger font, and more)
Here a screenshot: