1. An article comprising a machine-readable medium embodying instructions that when performed by one or more machines result in operations comprising: polling, by a script at a browser, one or more servers by sending messages to the one or more servers, the one or more messages soliciting one or more bids for presenting an ad at the browser and enabling access to information at the browser, the information relevant to the one or more servers making the one or more bids; receiving, at the script, one or more responses from the one or more servers, the one or more responses including the one or more bids; evaluating, by the script, the one or more bids; and selecting, by the script, one of the bids based on the evaluation, the selected bid corresponding to the ad.