The #1 Best Farming Spot in Cataclysm is the auction house. Not what you were expecting huh?
Here's why:
In the first few weeks Gathering professions are key. With the ability to show both mining and herbing nodes on the same character's radar at once it is now a cinch to collect tons of materials to sell on the auction house.
After the first month crafting professions start to be overtake by the sales of gathering ones.
How can you take advantage of this situation when materials and crafted items are so valuable early on in the expansion? Simply put: Addons and understanding markets.
You'll need to automate your auction house with helpful addons like auctioneer, postaland/or auction profit master. How great would it be if you could quickly search through the auction house for all the under priced herbs, gems or ore that players posted looking for quick gold after their farming sessions? You could then take those items and either relist them or use them to level professions which would make even more gold after a little investing in skill ups.
Imagine being able to scan for greens/blues to disenchant from all those players leveling up from 80 to 85 or even from 1 to 85 with a goblin or worgen in cataclysm.
Markets in world of warcraft behave in very specific ways throughout the week, so imagine being able to predict the values of various items in such a way that you can buy low one day and resell for much more a few days later? Then imagine repeating this process over and over again to accumulate ridiculous amounts of gold.
You can learn more about automation and understanding the markets of world of warcraft, cataclysm, in the link below this article.