The web can allow relative strangers to build up quite a detailed picture of you if you’ve ever used anything like myspace, flickr, facebook, etc. However, it can be deceptive or at least wildly unbalanced.
Reputation is crucial to something like ebay but it’s used more to red-flag untrustworthy users rather than provide a balanced picture. Users overwhelmingly give each other ‘AAA++++ would use again!!!’ ratings and expect the same back. Features like testimonials on Flickr also give the subject final say on filtering comments, so you know that isn’t going to be a complete picture.
The idea that anonymous feedback is generally the most accurate is behind the very new service The Gorb which is all about the honest truth. It allows anonymous users to rate online identities (i.e. e-mails) with a personal and professional value and add comments. The special GORB algorithm (maybe like Google page rank) supposedly weights ratings to address the problem of dissonant data. It isn’t perfect, of course, but is it better than current methods? I suspect the arguments against are similar to those used against Wikipedia.
Anyway, I’ve added myself as an experiment. Be truthful — I can take it! My reputation is in your hands.