19. A system according to claim 18 , wherein: the moderation score associated with a particular user-supplied rating is based upon a set of moderation scores each derived from user selection of a corresponding label from a plurality of labels that represent different levels of perceived credibility of the user that submitted the particular user-supplied rating.
20. A system according to claim 19 , wherein: the moderation score is generated by summing together the set of moderation scores and bounding the resultant sum by a predetermined maximum value and a predetermined minimum value.