This is tested and working as of now. Useful in PVP (Blade's Edge bridge, AB, AV, etc)
Play WoW in windowed mode. If you have a melee on you, jump off of whatever. When you jump, grab the side of your screen to resize (IE dragging the screen to make it larger or smaller- NOT minimize/maximize, but actually dragging the window). As long as you're resizing your screen your character will continue to fall server side, but on your computer you'll be in the same location. To melee however, you'll be out of range. Once you stop resizing you'll actually fall, take fall damage, and be able to be hit with melee attacks again. This is particularly useful if silenced or something necessary is a few seconds from CD.
I know this doesn't seem like a major exploit, but it is useful, especially in certain PVP situations.
Test it with your friends if you have any doubts. I just got done testing it for some time. Spells can still hit you while you're on the ground, however melee and pets WILL NOT be able to hit you. You'll be stuck in the air to them basically.
Enjoy.