Imaginary numbers

... or, the study of real economies in unreal places. (Link found via www.aldaily.com).

"Then he performed one final analysis: The Gross National Product of EverQuest, measured by how much wealth all the players together created in a single year inside the game. It turned out to be $2,266 U.S. per capita. By World Bank rankings, that made EverQuest richer than India, Bulgaria, or China, and nearly as wealthy as Russia.

"It was the seventy-seventh richest country in the world. And it didn't even exist.

"Castronova sat back in his chair in his cramped home office, and the weird enormity of his findings dawned on him. Many economists define their careers by studying a country. He had discovered one...."

Reason magazine has discussed related matters.