Putting aside for a moment that Skyrim is sure to be an incredibly deep and engrossing RPG experience with a very serious side, what sort of "just-for-fun" sandbox type activities would you like to get up to when you get your copy - what would you like to try out to see how well the game engine/radiant story system etc is able to keep up with your shenanigans? This can be as creative or as crazy/funny as you like, but try and keep it clean!
I want for endgame characters to be able to transform into dargons, which lets them fly, do special melee attacks, and cast more powerful versions of their normal dargon shouts.