via West County Explorers Club: A guy in the auto mechanics class I'm taking recently told me about a smart phone-based scan tool app called Torque. Scan tools are the devices you plug into your car or truck's OBD or OBD2 diagnostic port to display engine trouble codes, a handy thing to have if you're working on your own truck. (Trouble codes are generated by the vehicle's computer when the check engine light goes on.)
Besides reading trouble codes, the app can display all kinds of vehicle information on your phone or tablet in real time: mass air flow, boost (on turbocharged cars), coolant temp, fuel flow, the list goes on. And, because it's running on a smart phone, it can also display things like pitch, roll, GPS position, and compass heading. The app even has a function that will record video of the road ahead, through the phone or tablet's camera, while overlaying vehicle data into the frame. Pretty cool.
The video gives a good overview. Things start getting interesting around 4:06. Read more for additonal info and links.