Check out this demo reel of Levi Meeuwenberg doing some jaw-dropping "free running". Free running is very similar to Parkour in the athleticism required and specific techniques and movements used, but while Parkour is about getting from one place to another in as efficient a manner as possible, free running is less directed and more creative in nature.
As mentioned in that ancient post, when performing either of these activities, in addition to spending years developing a formidable set of technical skills, balance, physical strength, and kamikaze attitude, it's important to be cognizant of some basic physics.