Gravity Sports

Moving Downhill on a Board Skateboarding | Off Road In-Line Skateboard | Sandboarding
Moving Downhill in a Craft Go-Kart | Luge



Feet On Boots (Rock Skiing) | Skipping Downhill
Wheels
Downhill Mountain Biking (Winter) | ATB
Skiing
Alpine Skiing | Ski Bike | Downhill Ice Skating (Ice Cross Downhill) http://www.redbullcrashedice.com
Boards Sandboarding* | Snowboards --> Ice Boarding (down on ice) | Downhill Skiing | White Water River Boarding
Crafts Go-Carting | Ski Biking | Kayak slide | White-water sledging XXX | Zorbing | Ski Bob
Sliding Sand Sledding | Toboganning | Snowtubing | White-water rafting
Luge
Bobsleding | Luge | Ski Bob | Street Luge | Skate Luge (http://www.skateluge.com/)

Falling/Jumping
Freefalling Bungee* |  Sky Diving | Scad Diving& | Diving Planes
Jumping
Diving | Cliff Jumping | Coasteering | Abseiling | Barrel Jumping
Gliding
ParaglidingHangglidingGliding

Downhill/Fall Someone pushes you downhill ie Zorb | Machine to speed up freefall
Downhill/Fall
By ball | Item must be heavier than you

Animal Powered
Land Horse | Camel | Elephant | Donkey | Yak | Mule etc
Water Dolphin
Air Extinct large bird on low-g world



Moving Downhill on a Board
Skateboarding
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Off Road In-Line Skateboard

Dirtsurfer http://www.dirtsurfer.com/ http://www.exn.ca/dailyplanet/story.asp?id=2004092151 Off road in-line skateboard http://www.snowjapan.com/e/features/features-50.html Mountain Boards are for slower technical riding, inline skateboard for faster riding

Sandboarding
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Moving Downhill in a Craft

Go-Kart
Go karts are mostly a motorized sport -- an introduction to motor racing -- but sometimes go karts are powered with gravity with a person pushing the go kart to get it moving.
Go karting guide http://en.wikipedia.org/wiki/Karting