A recent (April 2011) World Bank report called “Converting the Virtual Economy into Development Potential: Knowledge Map of the Virtual Economy” has 60 fascinating 60 about the value of virtual economies for developing countries. Beyond well known WOW gold farming, the report touches upon micro work and related areas. This report is a must read for any virtual world practitioner and researcher (let alone policy makers and tax authorities).
I found these two tables to be of special interest to general audience (with my own highlight):
First the size of gaming market(total in 2011 – $18B)
and of the secondary market: ($3B) (secondary being defined as selling services and goods for the players and not the game developers).
To get all the details see:
Lehdonvirta, Vili. & Ernkvist, Mirko, 2011. Converting the Virtual Economy into Development Potential: Knowledge Map of the Virtual Economy, Washington, DC; infoDev / World Bank. Available at http://www.infodev.org/publications
See also European Central bank report on virtual currency schemes.