Ian Charnas was challenged to come up with a contraption that would enable "superhuman jumping." He succeeded, kinda. From MAKE:
I looked at using springs, stunt industry equipment, and even chemical propellants, before deciding to attach pneumatic pistons to some heavy-duty shoes. I calculated that at 200 PSI the jumping shoes should be able to get Tyler over 6 feet in the air, and followed guidelines from sports medicine research papers to make sure the forces on his feet would be within safe levels for athletes.