Jumping Off A Rollercoaster
At the 2009 New Jersey State Fair, a group of athletes demonstrating their astounding parkour skills for the crowd by jumping off of rollercoasters without safety nets, managing to land on the narrow bars below them using only their sheer physical abilities. It's amazing; watch the video to see for yourself.
Parkour, sometimes referred to as freerunning, is a French sport which has only recently become popular in the United States. If you're interested in learning the moves shown in the video, there may be classes in your city. Check it out.