Apparently my simulation idea about having students take on roles as career professionals has already been done. A drove of statistical consultants (the students) are helping the mayor (NPC), get re-elected.
The most interesting Worked Example is Modern Prometheus, where students learn about literature and writing through a MUVE.
But it is quickly becoming commonplace for people to spend a few dollars on them to get ahead in an online game or to give a friend a gift on a social network.
Most of the momentum in the virtual goods market comes not from gifts but from social games, where people buy items to improve their performance in the game or just to build up a collection that will impress friends.