I'm making a case that amazon.com should require their reviewers to sign their names. Real names. Hey, we can't throw eggs on them just because we know their name. Amazon can keep their other identifying info secret.
The reason I say this is because anonymity makes it really easy for people to heartlessly trash one of our books.
A lot of professional reviewers, like Harriet Klausner (amazon's Number 1 reviewer) or reviewers for some of the on-line review sites, are gracious enough to also post their reviews at amazon. Because these people sign their names, they are more apt to present a balanced review of the work.
Those who don't sign their names can make outrageous claims that are never substantiated.
I don't think you'll find many newspapers or magazines that will allow people to castigate someone -- or someone's work -- without identifying themselves.