A tag-mediated review system for electronic content that ranks content based upon several ascertainable factors, including the implicit engagement with the content by users (typically online viewers); the expertise and success in the topical domain by reviewers; and the review activity of users or viewers. The system extends implicit metrics to tracking of user interaction including the receipt of video and audio content over the web. Document ranking is mediated by tags that identify the subject matter addressed by an associated document as the ranking mediators for computing content quality scores values for user and reviewer activity. The tag-mediated content quality scores, which are content quality scores for the subject matter area identified by the associated tags, can be exposed to end-users and used directly or indirectly to complement search engine retrieval algorithms.