25. The non-transitory computer-readable medium of claim 24 wherein the plurality of content items are comments supplied by a plurality of human users, wherein the plurality of online information sources include one or more social networking services, wherein the indicated attribute is one of a plurality of terms included in contents of the content items of the identified subset, and wherein the stored contents include software instructions that, when executed, further cause the computing system to: determine, by the computing system and based on multiple third content items of the plurality of content items that are supplied by a first user of the plurality of human users, a further increase or a decrease in a third quantity of the third content items relative to a fourth quantity of multiple fourth content items of the plurality of content items that are supplied by one or more other second users of the plurality of human users; and provide, by the computing system, an indication of the determined further increase or decrease.
24. A non-transitory computer-readable medium having stored contents that cause a computing system to perform a method, the method comprising: obtaining, by the computing system and via electronic interactions over one or more computer networks, information from a plurality of online information sources including a plurality of user-supplied content items that are associated with multiple time periods and that are supplied to the online information sources; analyzing, by the computing system, the plurality of user-supplied content items, the analyzing including determining, for each of the multiple time periods, a quantity of the plurality of content items that are associated with the time period and have an indicated attribute; determining, by the computing system and based on multiple first content items of the plurality of content items that are supplied to a first information source of the plurality of information sources, an increase or a decrease for the first information source relative to one or more other second information sources of the plurality of information sources, wherein the determining of the increase or decrease is of a first quantity of the first content items relative to a second quantity of multiple second content items of the plurality of content items that are supplied to the one or more other second information sources; predicting, by the computing system and based at least in part on the determined quantities for the multiple time periods, an expected quantity of additional content items having the indicated attribute that will be supplied by users during an additional time period after the multiple time periods; and providing, by the computing system and via additional electronic interactions over the one or more computer network, information to one or more recipients that includes one or more indications of the predicted expected quantity of additional content items and of the determined increase or decrease for the first information source relative to the one or more other second information sources.