I've put this under Exploits as it goes against blizzard game mechanics.
Generally your not able to do anything during a flight, besides deleting things and the old /mountspecial macro.
During a flight from Orgi to Tanaris for the Trick'or'treat achievement, i clicked the "Weighted Jack-o'-Lantern" so as to see what would happen. Instead of the pumpkin going straight onto your character's head, it follows you for the duration of the journey possibly transfixing some of the more simple minded people, such as myself :homer:
Better than sitting there boring your balls of waiting for your destination, although probably not as exciting as going skydiving while waiting for your flight to complete.
:stick: