Higuys,
A few months ago, I picked up up a cool app for my Android tablet and I've used it a few times so far for driving on the track at Mid Ohio.
It's called aLapRecorder. www.adyno.net
First of all, the all the app can record HD video of the road ahead, if you mount your device so the camera can view the road.
It uses the GPS receiver to record location data, and the app calculates your speed, and displays that on the screen in some small gauge-like "dials." It will also display G forces from the device's accelerometer, and if you have an OBDII engine ECU, using a Bluetooth interface, you can also display engine RPM, trottle position, vacuum, Load/HP, torque, and other things.
If you load in the GPS data for a race track (provided free with the app) the app will calculate your lap and sector/Split times, and even show your position on an overlayed Google Map.If not, you can replay a track you just recorded and set up your own start/finish, sectors, etc.
After all that, you can export the data,video, display the data in graphic charts, and a bunch of other things.