From Surich Technologies:
AutoSpeed is an app that helps those pedal heavy drivers to slow down at the wheel by audibly giving a waring once you reach a certain speed.AutoSpeed takes advantage of the iPhone 3G GPS to calculate your speed and warns you when you have reached a certain speed limit.
====================================== This app supports units such as miles and kilometers. AutoSpeed also allows you to set the desired speed limit to warn you when you go over. ======================================
AutoSpeed comes with a speedometer gauge that gives you an estimate of your current speed. It uses advanced filtering algorithms to calculate your speed.
This app also provides you with the total time and distance traveled.
For best results AutoSpeed requires a clear view of the sky. You can also adjust the sensitivity level of the speedometer to give you a more consistent reading.
**Since this app uses the iPhone GPS it will only work on the iPhone 3G.