Abstract: A system for managing online advertisements, comprising a network-connected communications interface adapted to receive information from an end user interface and from an advertiser interface, an advertising server coupled to the communications interface, a pricing server coupled to the advertising server and to the communications interface, and a database coupled to the advertising server and the pricing server, wherein the pricing server, upon receiving a request for a price for a proposed online advertisement pertaining to a specific advertisement category from an advertiser interface, computes a price based at least in part on an indicia of available supply of advertisements pertaining to the category, said indicia obtained from the database, and provides the computed price to the requesting advertiser interface, and wherein the advertising server, on receiving a request for online advertisements pertaining to a particular advertisement category from an end user interface, retrieves all or a substantial p