1) Find a high place (that would probably kill you with fall damage);
2) Jump to the ground;
3) When you are near the ground, force quit Wow:
on Windows: Alt+F4
on Linux (in wine terminal): Ctrl+C
on Mac (in Wow icon): Quit Program
4) Relaunch the game and login you char;
5) You’ll start on the air (with zero acceleration) and will start to fall again;
6) Hit the ground with none or almost none fall damage.
* You can repeat this many times if you are not sure if you are near enough from the ground.
From www.***********.com