Magical Economy
This page details a collaborative project by /tg/ to create a complex, comprehensive system to simulate a medieval economy in magic settings like D&D after the fashion of Spice and Wolf or 3E's Magical Society:The Silk Road sourcebook, including a workable list of commodities and their values and the ability to take into account various factors such as supply and demand, transportation, economic bubbles, political and socioeconomic changes, and so on. The eventual aim is to have a system that can simulate medieval economy on the DM's side behind-the-scenes with reasonable accuracy.
"A program that could generate a random map, populate it, give weather patterns, provide trade, and a 'seed' that DMs could send around the world as an example of their game world."
Done creaming your pants yet? Good, you can get to work making this a reality.