After pondering for a while on why I'm so fixated on making meaningless numbers (such as LW karma or Khan Academy points) go up as a result of my actions, I came up with a hypothesis: the brain uses such numbers as a proxy for societal status. An experimental consequence of this idea is that status-seeking people and low-status people try harder (possibly also for longer periods of time) to achieve video game-style "points".
Just a thought, really. If this experiment has actually been done, it'd be cool to read about it if anyone has a link. I don't have the resources to do it myself. Anyone reading this comment who can do it is certainly free to, but I doubt that's the case.
Came up with the idea while responding to a question on Formspring.
It's called a token economy. Game developers use dark arts in all kinds of ways to keep people playing; they even employ PhD psychologists.
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.