My partner and I are working on a site featuring 3rd party services that will include user reviews of those services. Some of the service providers we would feature (our customers) have suggested that we should not allow anonymous reviews.
On one hand we agree that it would be great to be a forum supportive only of reviewers who are willing to stand behind what they say.
On the other hand, we think (1) it would be difficult to verify a reviewer's identity and (2) that review readers will tend to discount anonymous reviews on their own anyway so it will all come out in the wash. By that reasoning, there is no need for us to police reviewers, except for obviously inappropriate content or manipulative conduct.
We would love to hear how others think about this issue.