I've just been reading an interesting article on economists and video games; it seems that a fair number of other economists have thought about the research potential provided by virtual worlds, and at least two gaming companies—Valve (Steam) and the company that runs Eve Online—have found it worth hiring economists to help run their virtual economies.
I tried putting in a comment, but their registration software seems to be broken at the moment, so I decided to put the comment here instead, in the hope that my readers may include other economists with similar interests. Here it is:
Interesting article. I'm both an academic economist and a game player--WoW not EVE--and have been intrigued by the possibilities for years. Some time back, I had a blog post on the possibility of designing an economics course for students already active in WoW or something similar, using the game to teach economics.
Several years back my wife, who also plays, encountered a cartel on the auction house, was invited to join, declined, was threatened with predatory pricing—apparently the cartel operator wasn't familiar with the economics literature on the problems with that tactic. The attempt lasted for a couple of days before the cartel gave up. But I've observed continued, and apparently successful, efforts by the same player to push up the prices of various goods by buying up whatever anyone else puts up at a low price, then relisting it at a high price. Both my wife and I have engaged in occasional "auction house wars" with that player, undercutting her prices on something we produce in an attempt to drive the market price down.
On the general issue of arbitrage, it's worth noting that time is a cost and markets are often thin. So there may well be apparent profit opportunities that don't get exploited, due to the fact that the profit isn't enough to motivate someone to engage in arbitrage unless he also has fun doing it.
Reading your article, it occurred to me that someone ought to set up an email list for economists interested in virtual worlds.