SourceForge.net has implemented a project review or voting system, allowing users to vote up or vote down a project.
The project reviews are a simple tally of votes, Thumbs Up, or Thumbs Down for a project. Each user is afforded a single vote per project. When you visit a project on which you have logged a vote, you are offered the option to edit or remove that vote.
Users who are not logged in (authenticated) to the site who vote, will have their votes shown as from "Anonymous". However, if a user creates a vote or votes on 1 or more projects, on logging in via that same browser, that vote will be attributed to the now logged in username.
Users may also mark reviews as helpful or not helpful. This will help surface helpful reviews.
Project administrators can mark reviews as Spam if the review is either spam, or inappropriate (inappropriate language, etc.). This will hide the vote and will not add that tally according to the running vote count. These reviews will still be visible to the submitter as well as the project administrator who can go back and reverse the decision on a "spam" review.