It notes that in most games, players control the rate at which new cash is introduced into the economy. To avoid hyper-inflation, it recommends four steps:
Consumables are important in creating new Cash – If large amounts of new cash can be created without consumables, then there is no economic brake on cash creation.
Players set the prices of Consumable – This is the other side of the coin, since only player set prices can legitimately respond to changes in the money supply. Attempting to do this programmatically in such a diverse economy as a typical MMO is to invite failure. National governments have not been able to do this.
Fixed drains need to be in place – This provides a mechanism to remove a Crafter who is economically irrational from the business game, as well as to provide equilibrium in prices and money supply. Thus a regular fixed cash fee for doing business is required, and set by the game.
Variable Drains via percentage commission of the sale need to be in place – This provides a damper that mitigates wild swings in the money supply. Fictionally Sales commissions provide this damper. The percentage is set by the game, on Facility Type basis.
People building social games should read the whole thing.