You know how your friends' parents just have to see The Stones one more time before it's over? Well, unlike Keith, Mick, Charlie, et al--whose continued presence seems to belie all scientific research and suggest that they will never, ever die--a number of natural wonders won't be around in a few years. Hence our newfound obsession with "Tourism of Doom." Seriously, think about how cool it will be to tell your kids that you saw a glacier in person.