1. A non-transitory computer-readable medium embodying a program executable in a computing device, the program comprising: code that retrieves a first plurality of search queries returning an unclassified network site; code that retrieves a second plurality of search queries, individual ones of the second plurality of search queries returning a respective one of a plurality of classified network sites, individual ones of the classified network sites having at least one category; code that obtains a first attribute for the individual ones of the first plurality of search queries, wherein the first attribute represents a query competitiveness comprising a measure of a value of a respective search query to an advertiser; code that obtains a second attribute for the individual ones of the second plurality of search queries, wherein the second attribute represents the query competitiveness; code that combines the first attribute from the individual ones query in the first plurality of search queries into a first vector; code that combines the second attribute from the individual ones of the second plurality of search queries into a respective plurality of second vectors; code that selects at least one of the classified network sites based at least in part on a similarity between the first vector and individual ones of the respective plurality of second vectors; and code that assigns the at least one category of the at least one selected classified network site to the unclassified network site.