19. A computer-readable medium storing computer-executable instructions executed by a processor for causing a computer-controlled apparatus to implement a tag-mediated review system for electronic content, the executed computer-executable instructions performing a method comprising the steps of: obtaining on-line access to an infrastructure of a plurality of source documents, wherein each source document comprises source content supplied by an associated content producer and a plurality of content tags identifying subject matter contained within the source content; monitoring explicit sales metrics indicative of sales activity generated by user interaction with the plurality of source documents; computing a user rank for each source document based at least in part on the monitored explicit sales metrics indicative of user interaction with the source document; and computing a tag-mediated content quality score for each source document based at least in part on the computed user rank and tag scores for one or more of the content tags corresponding to the source document; compiling a content quality information database storing the tag-mediated content quality scores in association with corresponding content tags, user ranks, and identifiers of the plurality of source documents; receiving a document retrieval request; retrieving information identifying one or more source documents responsive to the received document retrieval request and the tag-mediated content quality score associated with the responsive one or more source documents; and displaying information identifying the responsive source documents and the associated tag-mediated content quality scores.
19. A computer-readable medium storing computer-executable instructions executed by a processor for causing a computer-controlled apparatus to implement a tag-mediated review system for electronic content, the executed computer-executable instructions performing a method comprising the steps of: obtaining on-line access to an infrastructure of a plurality of source documents, wherein each source document comprises source content supplied by an associated content producer and a plurality of content tags identifying subject matter contained within the source content; monitoring explicit sales metrics indicative of sales activity generated by user interaction with the plurality of source documents; computing a user rank for each source document based at least in part on the monitored explicit sales metrics indicative of user interaction with the source document; and computing a tag-mediated content quality score for each source document based at least in part on the computed user rank and tag scores for one or more of the content tags corresponding to the source document; compiling a content quality information database storing the tag-mediated content quality scores in association with corresponding content tags, user ranks, and identifiers of the plurality of source documents; receiving a document retrieval request; retrieving information identifying one or more source documents responsive to the received document retrieval request and the tag-mediated content quality score associated with the responsive one or more source documents; and displaying information identifying the responsive source documents and the associated tag-mediated content quality scores. 20. The computer-readable medium of claim 19 , wherein the explicit sales metrics indicative of sales activity for a particular source document comprise one or more of the following: purchases made by users after receiving information from the particular source document; repeat purchases made by users after having made an initial purchase after receiving information from the particular source document; links made by users to sites providing additional information regarding produces or services for sale after receiving information from the particular source document; and links made by users to affiliate commercial sites after receiving information from the particular source document.