11. The computer-readable medium of claim 8 , wherein the requesting computer user does not have an interest circle corresponding to the query topic.
8. A computer-readable medium bearing computer-executable instructions which, when executed on a computing system comprising at least a processor executing instructions retrieved from the medium, carry out a method for responding to a search query from a user, the method comprising: obtaining network navigation data of a first plurality of computer users, and for each of the first plurality of computer users: identifying a set of interest circles corresponding to the computer user based on the computer user's network navigation data; and storing the set of interest circles in an interest circles store in association with the computer user; receiving a search query from a requesting computer user, the search query being directed to a query topic; obtaining a set of search results responsive to the search query; and determining whether the requesting user has an interest circle corresponding to the query topic and, upon the condition of determining that the requesting user does not have an interest circle corresponding to the query topic: identifying a second plurality of computer users, each of the second plurality of computer users being identified as having an established interest circle corresponding to the query topic, wherein identifying the second plurality of computer users comprises identifying the second plurality of computer users irrespective of any user-established relationship with the requesting computer user; ordering the set of search results according to the interest circles of the identified second plurality of computer users; and returning higher ordered search results to the requesting computer user.