5. The computer-readable medium of claim 1 , further comprising the steps of: receiving a plurality of reviews concerning a plurality of electronic source documents associated with a particular content producer; computing a tag-mediated content producer rank for the particular content producer based on the reviews concerning the plurality of electronic source documents associated with the particular content producer that includes tag scores for one or more tags in the electronic source documents; storing the tag-mediated content producer rank in the content quality information database in association with an identifier of the associated content producer; and wherein the computation of the tag-mediated content quality score for each source document associated with the particular content producer is based at least in part on the content producer rank for the particular content producer.
5. The computer-readable medium of claim 1 , further comprising the steps of: receiving a plurality of reviews concerning a plurality of electronic source documents associated with a particular content producer; computing a tag-mediated content producer rank for the particular content producer based on the reviews concerning the plurality of electronic source documents associated with the particular content producer that includes tag scores for one or more tags in the electronic source documents; storing the tag-mediated content producer rank in the content quality information database in association with an identifier of the associated content producer; and wherein the computation of the tag-mediated content quality score for each source document associated with the particular content producer is based at least in part on the content producer rank for the particular content producer. 7. The computer-readable medium of claim 5 , wherein the step of computing the tag-mediated content producer rank for the particular content producer further comprises the steps of: obtaining explicit sales metrics indicative of sales activity resulting from user interaction with the electronic source documents associated with the all content producers represented in the content quality information database; obtaining explicit sales metrics indicative of sales activity resulting from user interaction with the electronic source documents associated with the particular content producer; and normalizing the content producer rank for the particular content producer based on the explicit sales metrics for the particular content producer and the implicit engagement metrics for all content producers represented in the content quality information database.