Here is an innovative concept that completely rethinks traditional luggage design. Called the Samsonite OBAG, it utilizes a diwheel arrangement to make traversing virtually any terrain a breeze. It will have no problems tackling snow, mud, cobblestones or even flights of stairs and saves you from worrying about flimsy wheels falling off. Designed by Rooz Mousavi, the OBAG is a brilliant implementation of diwheel design. (Link)