At random moments in the game, the shopkeepers of Whiterun (and possibly elsewhere) will sell a "Miscellaneous" item called "Do Not Delete". It appears to be a common treasure chest. However, much like the paintbrushes in Oblivion, they have no laws of gravity applied to them. When you drop them, they float wherever your cursor was. Buy two of them to get into areas you couldn't reach before, or (if you have the time) create a stairway to the sky.