I have been doing this since Wotlk was released and I figured It was about time I shared this. Now I searched and I could not find anything like this or about this, however if I am wrong I apologize.
Make your way to Amber ledge in Borean Tundra.
Next you will want to fly to Warsong Hold and sit on your flyer as you wait for the Zeppelin.
Board the Zeppelin where you see me doing it.
Now just sit back and let it fly you to Orgrimmar! Once you arrive jump down to your left and do what you want.
Now before people start QQing saying this has been done in the past with other zeppelin routes or that this is not an exploit etc. If you do it this way you will never get aggro or have to run through countless hostile npc's. Also this is 100% an exploit due to the fact that you are using your flyer to avoid Hostile npc's that would keep you from getting onto the zeppelin or staying on it.
Enjoy!