Are iPhone apps getting cheaper from the amount of competition out there, or are more gifted humanitarians turning into programmers?
The SpeedClock app measures both distance and speed to an object, and it costs a dollar. Become a fake road cop, measure your dog, there are many fantasy avenues possible with this if you want to make sure your buck is well spent.
It has a three axis gyroscope that, together with some trigonometry, gets the distance measurement. Speed is a simpler affair, doing some motion match with the video cameas of the iPhone 3Gs, iphone 4, and iPod touch 4.
Those are, of course, the Apple devices the app is compatible with. Of the bunch, the 3Gs has no gyroscope, so it’ll be less accurate.