I’ve been reading a lot about online gaming. The worlds are so real to people that they not only spend hours playing but they spend real money buying objects, homes and even land in the virtual world. You can check out the exchange rate for the gaming currencies on Ebay. Money in Everquest or Sims Online is worth real US dollars!
This article in USAToday, Virtual real estate boom draws real dollars, talks about virtual land in Second Life that goes for $550/acre!