Maps for Speed: adds the speed at which you in your native application Google Maps (Cydia)

Speed ​​Maps for add a speedometer in the bottom right corner of your screen in the native Google Maps application. You can configure it to give you the speed in miles per hour, feet, kilometers, meters per second, knots ... (from settings of your iPhone)

The truth is that when I go in the car using a browser, not google maps, google maps street use it to find something and there's no need to measure speed, but hey, sure there is someone that seems useful and that is what important.

You can download it for free on Cydia.
Need to be jailbroken.