15. A non-transitory computer readable medium having stored thereon sequences of instructions including instructions that will cause a processor to perform a method of delivering advertising comprising acts of: receiving, by the processor configured to perform functions associated with an e-commerce website, signals from at least one advertiser including an advertising campaign including one or more advertisements for one or more advertised products; associating the one or more advertisements with one or more keywords, each of the one or more keywords representing the one or more advertised products; transmitting, by an interface coupled to the processor, web page signals over a communications network, to a web browser operated by a client computer, the web page signals configured to operate the web browser to display a web page associated with the e-commerce website; receiving, in real time from a publisher of the e-commerce website, a request to display an advertisement on the web page; receiving, in real time, client activity signals from the client computer over the communications network, the client activity signals corresponding to real time activity of a user interacting with the web page of the e-commerce website via the web browser; determining, in real time, an intent of the user interacting with the web page of the e-commerce website via the web browser to purchase a product based on one or more user supplied keywords represented by the client activity signals; identifying, with a hurdle rate engine in the processor configured to perform functions associated with the e-commerce website, a hurdle rate set by the publisher of the e-commerce website, the hurdle rate being based on the intent of the user to locate the product for purchase and identifying a threshold amount to be bid by an advertiser in order to display an advertisement in a portion of the display shown the user on the web page via the web browser, the threshold amount of the hurdle rate being set by the hurdle rate engine at a level configured to prevent a loss of expected transaction revenue if the advertisement is displayed to the user via the web page; dynamically adjusting, with the hurdle rate engine, the hurdle rate set by the publisher of the e-commerce website responsive to real time updates of the intent of the user; determining whether to display, in the portion of the display shown the user, at least one of the one or more advertisements, wherein the act of determining includes an act of changing the at least one of the one or more advertisements based on the dynamically adjusted hurdle rate; and transmitting, by the interface over the communications network, display signals associated with the at least one of the one or more advertisements to the client computer in response to the at least one of the one or more advertisements being associated with the one or more user supplied keywords and having a bid that exceeds the dynamically adjusted hurdle rate, the display signals configured to operate the web browser to display, in real time, the at least one of the one or more advertisements in the portion of the display shown the user on the web page associated with the e-commerce website.
16. The computer readable medium according to claim 15 , wherein the request includes information related to the intent of the user.