I couldn't find this exploit on the forums but it was easy to find out so I am not surprised if it's already here :/. This trick is great for healers.
This exploit requires you to have:
The Last Line Of Defense - Quest - World of Warcraft
Taking Battle To The Enemy - Quest - World of Warcraft
At The Enemy's Gates - Quest - World of Warcraft
Works for both Alliance/Horde.
If you have read the quests, you should immediately know what is going on.
If not, this is the instructions.
Use the cannons in the fort from the quest
The Last Line Of Defense - Quest - World of Warcraft and shoot at the spiders until you complete the other 2 quests.
Then drop the quest:
The Last Line Of Defense - Quest - World of Warcraft
Do this everyday and it will save a lot of time. And of course, this is only possible if you have not completed the first quest.