21. The method of claim 5 wherein the plurality of comments are supplied by the human users to a plurality of information sources, and wherein the method further comprises: determining, based at least in part on a first subset of the plurality of comments that are associated with a first information source of the plurality of information sources, an increase or a decrease in a first quantity of comments in the first subset relative to a second quantity of comments in a second subset of the plurality of comments that are associated with one or more other second information sources of the plurality of information sources; and providing one or more indications of the first information source and of the determined increase or decrease.
5. A computer-implemented method comprising: obtaining, by one or more configured computing systems and via electronic interactions over one or more computer networks, information from one or more network-accessible sites including a plurality of comments that are supplied by human users to the one or more network-accessible sites over multiple prior time periods and that are related to multiple topics; analyzing, by the one or more configured computing systems, and for each of the multiple prior time periods, multiple textual comments from the plurality that are for the prior time period to identify a subset of the multiple textual comments whose contents are associated with a specified content category; determining, by the one or more configured computing systems, and for each of the multiple prior time periods, a quantity of the identified textual comments for the prior time period that are associated with an indicated topic from the multiple topics; predicting, by the one or more configured computing systems, and for each of multiple future time periods, an expected quantity of future textual comments associated with the indicated topic that will be supplied by human users during the future time period, the predicting being based at least in part on the determined quantities for the multiple prior time periods; and providing, by the one or more configured computing systems and via additional electronic interactions over the one or more computer networks, information to one or more recipients that includes, for each of one or more of the multiple future time periods, an indication of the predicted expected quantity of future textual comments for the future time period.