My daughter in New Zealand was telling me about "zorbing." Here's a link to the first US zorb "center" in Tennessee: http://www.zorb.com/smoky/ Some fun stuff on YouTube too!
"theres also water zorbing. thats when you have water IN your zorb." my friends and i had a little bit of an adventure last year looking for this kinda stuff, but overall too darn expensive.
I wanted to do this before, but when I looked in to it I discovered that it's a very rare activity here in the states. That made me wonder if there's money to be made in launching some Zorb sites, or if there's simply no market for it yet either due to costs or lack of interest.