1. A computer-implemented method comprising: causing, by a server system via a network, a web browser to display (a) at least first and second content areas separately from each other on a webpage, and (b) at least a first content item at a location on the webpage other than in the first and the second content areas; receiving from the web browser, by the server system via the network, an indication of dragging, by a user of the web browser, of an element displayed on the webpage, and dropping, by the user, of the element into one of the first and the second content areas, the element selected from the group consisting of: the first content item, and a graphical element displayed in association with the first content item; if the indication is of dropping the element into the first content area, causing, by the server system, the web browser to display, in the first content area, at least a portion of a set of one or more second content items related to the first content item; and if the indication is of dropping the element into the second content area, causing, by the server system, the web browser to display, in the second content area, at least a portion of a set of one or more third content items related to the first content item.