Here's something fun: a bunch of scientists decided to get together and do some field research, and assembled a conference. In Azeroth. They published their findings in the American Association for the Advancement of Science's magazine, and it's an entertaining read:
Thus began the first scientific conference held in Azeroth, the online universe inhabited by millions of people playing World of Warcraft. Anyone who has been part of a conference's organizing committee knows that some glitches and mishaps are just unavoidable. And as usual, the problems that actually did occur were unforeseen. It was a success nonetheless. By the end of the third day, a real scientific exchange took place, I married one of the conference participants, and within an hour of the wedding, we were all dead.
There are a lot of feel-good stories circulating about how scientists are using online games to study behavior, but this one is a lot of fun.