Rockboard's Descender board is equipped with treads wrapped around heavy rollers. It's built to go over terrain completely impassible for normal skateboards. Would you enjoy riding it?
Cool! However I'd like to see a video demo on a surface you can't ride down with ease using a board that can also ollie on pavement. I used to ride down a grassy hill identical to that one every day on my way to school, and that was during the ridiculously tiny-wheel era (early 90s)
http://en.wikipedia.org/wiki/Grass_skiing