22. A non-transitory computer-readable medium storing software comprising instructions executable by one or more computers which, upon such execution, cause the one or more computers to perform operations comprising: obtaining identity information, with a portable program module, for a source of a webpage associated with a container document, the portable program module located in the container document; submitting, by the portable program module located in the container document, the identity information to a concept server storing keywords associated with the container document; receiving, by the portable program module located on the container document and from the concept server, in response to the submitted identity information, the keywords associated with the container document; selecting, by the portable program module located in the container document, a subset of the keywords received from the concept server based at least on one or more criteria specified by an author of the portable program module; submitting, by the portable program module located in the container document, a query to an item search server related to the subset of the keywords selected by the portable program module; and receiving, at the portable program module located in the container document, advertisements responsive to the query from the item search server for display.
22. A non-transitory computer-readable medium storing software comprising instructions executable by one or more computers which, upon such execution, cause the one or more computers to perform operations comprising: obtaining identity information, with a portable program module, for a source of a webpage associated with a container document, the portable program module located in the container document; submitting, by the portable program module located in the container document, the identity information to a concept server storing keywords associated with the container document; receiving, by the portable program module located on the container document and from the concept server, in response to the submitted identity information, the keywords associated with the container document; selecting, by the portable program module located in the container document, a subset of the keywords received from the concept server based at least on one or more criteria specified by an author of the portable program module; submitting, by the portable program module located in the container document, a query to an item search server related to the subset of the keywords selected by the portable program module; and receiving, at the portable program module located in the container document, advertisements responsive to the query from the item search server for display. 24. The medium of claim 22 , wherein the operations further comprise displaying the advertisements within the container document, wherein the advertisements include one or more hyperlinks.