Has there been any research on how to prevent what you might call the “volunteer-power-hunger” that occurs in communities where there’s emphasis on community moderation?

It would be interesting to get an economist’s take on how to improve these sites.

In particular I’ve found it strange that the karma community on various sites doesn’t “charge” you to do more things. For example on this site it would make sense if it costed you karma to up vote and downvote - this would create an emphasis to not spend too much so to speak.