I love stackoverflow.com. To the unfamiliar: it’s simply a programming Q&A site where you post your problem and strangers solve it for you. There are hundreds of other Q&A sites, but Stack Overflow has hit a home run with fantastic implementation and an addictive game-like feel where you earn “reputation” points and achievements for good questions or answers. It has become as profoundly useful in my day-to-day work as Wikipedia.
Today I achieved a trivial little milestone of 3000 reputation which grants me the power to close/reopen questions. I probably won’t use that privilege, but it’s an example of a site feature that sucks you in and makes you want to use it more – positive reinforcement.
I briefly considered whether Wikipedia would benefit from similar gamification, but I think it would not. Stack Overflow incentivizes quick but thoughtful answers to individual, specific question while Wikipedia tries to build a coherent representation of a broad base of knowledge. Quick incentives would be a negative in Wikipedia, I think.