4. The method of claim 1 , wherein identifying the first set of documents comprises applying the search query to a first document database that includes references to documents that are classified as belonging to the first category; and wherein identifying the second set of documents comprises applying the search query to a second document database that includes references to documents that are classified as belonging to the second category, the second document database being different from the first document database.
1. A computer-implemented method comprising: receiving a search query; identifying a first set of documents that are each (i) responsive to the search query, and (ii) classified as belonging to a first category of documents; identifying a second set of documents that are each (i) responsive to the search query, and (ii) classified as belonging to a second category of documents; determining a relevance of the first set of documents relative to the second set of documents based on (i) a relevance of the documents of the first set to the search query, and (ii) a relevance of the documents of the second set to the search query; determining a layout of a search results page in which links to one or more documents of the first set and links to one or more documents of the second set are to be presented based on the relevance of the first set of documents relative to the second set of documents, comprising: determining, based on the relevance of the first set of documents relative to the second set of documents, a size of a first area of the search results page in which the links to one or more documents of the first set are to be presented; and determining, based on the relevance of the first set of documents relative to the second set of documents, a size of a different, second area of the search results page in which links to one or more documents of the second set are to be presented; and providing, for display, the search results page.