Skateboarding without legs.
For me skateboarding is fascinating. They weren't around when I was a kid and they frighten the crap out of me although I did land kite with a mountain board before taking to the water.
Check out this video if you haven't already seen it. This guy has achieved stuff no ordinary mortal would contemplate and has used skateboarding as the extreme expression of the resilience of the human experience when the spirit remains.