Recently I worked on a review extension for the Omaha Wiki. They wanted to give users of the wiki the ability to write reviews for pages, while still keeping control of the content and separating the factual information from the opinions.
Initially I just worked on adapting the Rating extension by Sanford Poon, but it was getting hard to deal with and make all the changes that were needed, so I started over.
The end result is VCReviews which combines the rating and review process into one submission, and is only accessible by logged in users. You can check it out at the Omaha Wiki. Just pick an article and click on a "reviews" tab.
Source is available: VCReviews Version 0.2.2