The GoPro Hero is a digital camera can capture clear and crisp HD video. What makes it unique is tough construction, fisheye lens and the ability to mount to just about everything including the underside of a car.
In this video, YouTube User NickInTimeFilms mounted a GoPro camera to the rear sway bay of his Honda CRV to diagnosis a scrapping brake noise. It is easy to see the caliper guide pin bolt is missing.
I have to admit this is a slick way to look for noise and other brake problems. At approximately $200, the GoPro has an advantage over more expensive chassis microphones and a huge advantage over the test drive with your head out the window.