I've spent some years being a merchant on various MMO's, and I've been wanting to branch out and find new MMOs to merch. I figured the best way I could do that is if I, through the assistance of the users on this forum, created a list of MMOs focused on their economic and merching aspects.

One of the quickest ways to know what a merching experience will be like is through knowing some key aspects of the in-game economy. There are some features and traits of MMO economies which have profound impacts on merching gameplay. Some clear examples would be auction houses, free/restricted trade, and playerbase.

I'd like this thread to be a brainstorming thread. What do all of you think are some of the most economy-defining characteristics of MMO's?

-Presence of Auction House and/or trade system
-Market Freedom (free or restricted trade)
-Single or multiple currencies
-Strength/presence of black market
-Player-owned shops
-Diversity in items
-Inflation tendencies
-MMO age
-Wealth stratification

Any help is much appreciated. More traits, in-game examples, and whatever else you can provide is encouraged.
Thanks to everyone who posts!