gRide Lite

gRide is an application that measures the total G-forces influencing the device in the x, y, and z directions. The gauge at the top and the graph at the bottom, record the maximum Gs reached while the graph in the middle displays the instantaneous Gs. To use gRide, simply launch the application and place the device somewhere in a way such that it doesnt move, then reset the max and start your run. There is no calibration required and the phone can be place in any orientation desired.
In the full version of the app, you can also change the skin, email your data, and it is not limited to 0.75Gs like this Lite version.

This application works with many different types of vehicles such as cars, boats, aircraft, or even a roller coaster. Just start the application, reset the max Gs, and record away.