Making Money In MMORPGs

I recently got a spare laptop, and I'm looking into playing some games with it, but I'd rather play one that I can earn some money off of. I'm not really looking to get rich by playing games, rather, I would just prefer that if ever I was to spend a significant amount of my time playing a game, that it at least be one that pays. That being said, I know a lot of current games now such as Diablo 3 will allow you to trade and profit from items. I'd just like to know if anyone here would have any particular game they could suggest that might be better or more profitable than D3?