I think everyone has heard of the new Insane in the Membrane Title, rewarding people with the ''The Insane'' Title. (Insane in the Membrane - Achievement - World of Warcraft)
One of the requisites for this title is obtaining exalted with the Darkmoon Faire.
The only way to get reputation with the Darkmoon Faire past honored is by handing in decks, for 350 rep each, meaning a godload of money just to get exalted, easily 20k gold.
With 3.1 blizzard introduced a change with the decks, making them BoE when obtained from the quest, thus resellable.
Alot of people who are aiming for ''The Insane'' Title are currently in trade saying something like ''Let me handin your darkmoon deck so I get the rep for the Insane achievement paying 50g if you let me do that''.
Now you can easily take advantage of that, because most decks are worth 500g atleast.
Make your own /2 Let me handin your Darkmoon Deck please, im aiming for the ''Insane'' Achievement,which requires Darkmoon Faire Exalted, paying 50g.
For the average costumer this looks like a pretty good deal, the Darkmoon Faire rep they get is completely useless to them, they help another player and earn 50g in the proces.
They trade you their deck while you trade them 50g, for a deck thats actually worth ~500g, hand it in and then log off.
Most of the scams that involve this are easily proven and banable, but this one isn't, since you technically pay 50g for the deck and then its yours, so blizzard cannot ban you on this.
I have currently made about 15k with this scam alone and havn't been banned