When I say insane, I mean insane. Each trip you do this youll get at least 13,500 xp per run. This will work for alliance if they have a similar area. When you go to Warsong Hold in the quarry place there are lots of 'nerubian victims' which look like people wrapped in white spider silk. The victims have about 400 health, so they should die in 1 fast hit. They are all over the place, theres practically 1 in every corner of each space. When you kill one of these a shaman, mage, or warrior can appear and will fight with you for a short while. The roles are similar to player roles - shamans heal (most of the time), warriors tank and melee dps, and mages go pure dps.
This works best with 2-3 people.
Get in the quarry (potions, elixirs, scrolls, ext. are neccesary) run like hell in your wing (if your alone) or across the quarry (if you are with friends) just shooting every victim you see until you get to a dead end. By this time it will be you, your friend(s) if you are with them/him/her, an army of horde fighting nerubians by your side, and a ton of nerubians getting owned by you and your army. Make sure to AOE or just run around attacking each nerubian a little bit at the start so you get the loot and XP.
You will get at least 13,500 XP a trip and countless leather, + all the gray items you can sell. This is flawless, but i am sorry if this should have gone under guides, or if it was a repost.
EDIT:: Could a moderator or admin move this post to the Guides Forum? Much Appreciated.