16. The non-transitory computer-readable memory device of claim 11 , where the one or more instructions to obtain the set of one or more addresses include: one or more instructions to present a hierarchical directory of category listings to the user, each of the category listings including an associated list of addresses, one or more instructions to receive one or more selections of the category listings from the user, and one or more instructions to include the associated list of addresses, corresponding to each of the one or more selections of the category listings, in the set of one or more addresses.
16. The non-transitory computer-readable memory device of claim 11 , where the one or more instructions to obtain the set of one or more addresses include: one or more instructions to present a hierarchical directory of category listings to the user, each of the category listings including an associated list of addresses, one or more instructions to receive one or more selections of the category listings from the user, and one or more instructions to include the associated list of addresses, corresponding to each of the one or more selections of the category listings, in the set of one or more addresses. 17. The non-transitory computer-readable memory device of claim 16 , where the one or more instructions to receive the one or more selections of the category listings include: one or more instructions to add a first one of the category listings, corresponding to first subject matter that is on-topic relative to a topic of the search query, to a positive preferences list, and one or more instructions to add a second one of the category listings, corresponding to second subject matter that is off-topic relative to the topic of the search query, to a negative preferences list.