Ahh, gold farming. It is, if you'll excuse the pun, a gold mine of comedy. This was proven most recently in the webcomic Extralife, which shows us a meeting between a player and an enterprising businessman.
Actually, while this is obviously humor, it does give one pause to consider what sort of life the actual farmers must lead. As with all such low-skilled labor, the profits for the people in charge are probably much greater than what the actual workers receive. That line about feeding the whole family for 3 months ... is it funnier if it's true, or just horrible?