4. An apparatus for organizing a collection of documents, comprising: memory hardware storing program instructions, and one or more processors in data communication with the memory hardware and configured to execute the program instructions, and upon execution the program instructions cause the one or more processors to perform operations comprising: identifying a plurality of documents responsive to a search query, wherein the plurality of documents include at least one document visited by multiple distinct counted visitors during a time period; accessing usage information associated with the plurality of documents, the usage information including, for each document, (i) a frequency of visit value based on a total number of times the respective document was visited by all counted visitors visiting the document during a time period, and (ii) a unique visit value based on a number of unique visitors among all counted visitors visiting the respective document during the time period; determining, for each document, a usage score from the frequency of visit value and the unique visit value associated with the respective document; and organizing the documents based, in part, on the usage scores for the documents.
4. An apparatus for organizing a collection of documents, comprising: memory hardware storing program instructions, and one or more processors in data communication with the memory hardware and configured to execute the program instructions, and upon execution the program instructions cause the one or more processors to perform operations comprising: identifying a plurality of documents responsive to a search query, wherein the plurality of documents include at least one document visited by multiple distinct counted visitors during a time period; accessing usage information associated with the plurality of documents, the usage information including, for each document, (i) a frequency of visit value based on a total number of times the respective document was visited by all counted visitors visiting the document during a time period, and (ii) a unique visit value based on a number of unique visitors among all counted visitors visiting the respective document during the time period; determining, for each document, a usage score from the frequency of visit value and the unique visit value associated with the respective document; and organizing the documents based, in part, on the usage scores for the documents. 22. The apparatus of claim 4 , wherein organizing the plurality of documents comprises organizing the plurality of documents in a descending order of relevance based on the usage scores for the documents and information retrieval scores that measure a relevance of the documents to the search query.