Online, Anonymity Breeds Contempt - NYTimes.com
This is a thoughtful piece on the dangers of anonymity on the web, and it certainly makes valid points, and raises clear examples of places where anonymity allows people to do all sorts of ugly things.
However, there is another side to the argument. There are times when anonymity allows people the freedom to speak the truth and to challenge authority. It is just a question of knowing what types of anonymity we need to keep and which we are better off without.