For straight cash farming I always liked a combat rogue. Sure it isn't as spectecular as some AOEing mage but if the equipment is good you can basically chain kill a lot of mobs throwing a bandage here and there.
You also have the ability to vanish when something goes wrong and to sneak through crowded places to farm ore or herbs. Plus since combat requires only two or three buttons for farming you can watch TV or do whatever you like and don't have to concentrate on wow too much.
Before BC there were bosses that were and killable solo for the disenchanting although I doubt that there are any of those in the outlands.
Bunny
(former combat rogue before I got tired of raiding)