Ripxx is a water and shock proof gadget that uses 3 accelerometers and 3 gyroscopes to record your path speed, vertical drops, spins and falls for playback on your computer later.
It also reports time of run, top acceleration, speed, jump data (time in air, distance, height), rolls (count and rate), top altitude and steepness of runs. The 3d playback of your data is done in third person, over 3d terrain.
You'd figure there would be an app for this already but there's no doubt in my mind that if its good enough for the US bobsled team, all those sensors and gyroscope must be good enough for me. [ripxx via Popsci]