Bruce Schneier notes this example of in-game surveillance in World of Warcraft. You can see the project blog from the PARC PlayOn ("Exploring the social dimensions of virtual worlds") project to read about guild churn, how much time elite players are spending in raids, and how WoW level 60 (top) players are different from their less experienced counterparts. Lots of online sociology here, mostly conducted without IRBs and player consent into being watched and studied.
I'm on the lookout for comprehensive in-game transaction and economic analysis as well.
Thanks to Jose Nazario for this pointer (and thanks for lunch Jose, I owe you one).