I'm not convinced reputation systems are a good thing. 1) only sites that need a community identity can benefit from such a system, 2) the system allows for arbitrary prejudice, and 3) its utilization is extraneous for building trust and admiration among the real contributors (the users so influential they get referred to by their actual names).

Craigslist is what it is because of its anonymity. On Amazon I usually only buy from sellers with plus 98% approval rating, but I only do so arbitrarily and rarely read customer reviews. I feel a simple comment system, like they have implemented to gauge the actual product itself, would be appropriate; if someone gets scammed that person can write about the experience, conversely, if one's expectations are exceeded then that person can say so as well. Both ways I'm comparing are still subject to slander but value systems distort transparency in the outlier data where one bad comment can destroy a newbie and one bad but genuine rating on a purposed sketchy veteran will just be another notch on his belt.

It's sad but since I only have 9 karma points on HN I doubt anyone will comment on this, and if so only to be ironical. Just like school or any value system, its constituents are greatly subject to conflicts of interest that may coerce corruptive and erosive behavior. In communities where karma is recognized as superficial (like HN, we're all programmers mostly--hopefully the issue is taken lightly) points are a fine means for getting quick feedback and are seemingly harmless. But when you slap that point sticker on your username things turn ugly; it's just too easy to misjudge someone based on this criteria alone instead of empirically. This especially holds true for newcomers and passersby, no?

Kuler is a perfect example of a community done right. The community is this perfect size and the most involved and valuable contributors encourage, if not mentor, newcomers who show genuine interest in the site. The Kuler community has a superficial reputation system, meaning there is no explicit currency or status. Users on the site build relationships, not status, and I feel personally responsible for the content I produce there. It's a positive feedback loop running mostly on respect at Kuler, not a negative one. Points should be associated to the content of a user and not the user itself as a means of recognizing quality--isn't the basis of this idea what that whole crazy internet thing was about back in the 90's?

Some might claim that token economies encourage responsibility but I say they overwhelmingly generate irresponsibility (if done mediocrely or less) as their superficiality moves ever closer to reality. Maybe the times have corrupted my tongue but these electronic reputation systems are increasingly turning into viable currency that some are willing to exchange real money to possess. If you decide on incorporating a token economy into a community please make sure the currency is distributed and controlled by the users. I not sure if anyone else out there does this but every time I use craigslist I quietly mutter under my breath "Thank you Craig for keeping it simple."