Have wow windowed right click the title bar and hold it the game will appear frozen whilst you hold it and your character will have stopped falling.
Do this when the valkyrie drops u in the lich king fight wait till the next phase wen the ground reappears and let go perhaps you will land on the ground instead of falling to your death.
Tested this with the elevator in shaterah jumped at the top whilst the elevator was at the bottom held it for a few seconds and landed when it was at the top with no fall damage.
P.s also useful for exploration as discovered by Feroid further down the page.