6. A system, comprising: one or more computers; and computer readable media coupled to the one or more computers and storing software instructions configured to cause the one or more computers to perform operations comprising: receiving first content authored by a first author; determining that the first author has no assigned rating; and in response to determining that the first author has no assigned rating: identifying attributes of the first author; identifying other authors that are not authors of the first content, each other author having one or more attributes in common one or more identified attributes of the first author and not an author of the first content, and wherein at least one of the other authors has at least one attribute not in common with the first author; for each identified attribute of the first author in common with an attribute of one or more other authors, generating a rating for the identified attribute based on ratings that are assigned to the other authors having the attribute, the ratings that are assigned to other authors being based on user feedback; generating an initial content rating for the first content based on the ratings for the identified attributes; and assigning the initial content rating to the first content.
6. A system, comprising: one or more computers; and computer readable media coupled to the one or more computers and storing software instructions configured to cause the one or more computers to perform operations comprising: receiving first content authored by a first author; determining that the first author has no assigned rating; and in response to determining that the first author has no assigned rating: identifying attributes of the first author; identifying other authors that are not authors of the first content, each other author having one or more attributes in common one or more identified attributes of the first author and not an author of the first content, and wherein at least one of the other authors has at least one attribute not in common with the first author; for each identified attribute of the first author in common with an attribute of one or more other authors, generating a rating for the identified attribute based on ratings that are assigned to the other authors having the attribute, the ratings that are assigned to other authors being based on user feedback; generating an initial content rating for the first content based on the ratings for the identified attributes; and assigning the initial content rating to the first content. 7. The system of claim 6 , the operations further comprising eliminating the initial content rating after receiving a user feedback based content rating for the first content.