11. A computer-readable memory device, comprising: a plurality of computer-executable instructions, which, when executed by one or more processors, cause the one or more processors to: determine a first average amount of time that a first set of users spent accessing a document during a first time period; determine a second average amount of time that a second set of users spent accessing the same document during a second time period, the second time period occurring after the first time period; compare the first average amount of time to the second average amount of time determine, based on the comparing, that the first average amount of time is different from the second average amount of time classify the document as stale or fresh based on determining that the first average amount of time is different from the second average amount of time, when classifying the document, the one or more devices further being to: classify the document as stale when determining that the first average amount of time is greater than the second average amount of time, and classify the document as fresh when determining that the first average amount of time is less than the second average amount of time generate a score for the document based on classifying the document as stale or fresh; and rank the document with regard to at least one other document based on the generated score.
11. A computer-readable memory device, comprising: a plurality of computer-executable instructions, which, when executed by one or more processors, cause the one or more processors to: determine a first average amount of time that a first set of users spent accessing a document during a first time period; determine a second average amount of time that a second set of users spent accessing the same document during a second time period, the second time period occurring after the first time period; compare the first average amount of time to the second average amount of time determine, based on the comparing, that the first average amount of time is different from the second average amount of time classify the document as stale or fresh based on determining that the first average amount of time is different from the second average amount of time, when classifying the document, the one or more devices further being to: classify the document as stale when determining that the first average amount of time is greater than the second average amount of time, and classify the document as fresh when determining that the first average amount of time is less than the second average amount of time generate a score for the document based on classifying the document as stale or fresh; and rank the document with regard to at least one other document based on the generated score. 15. The computer-readable memory device of claim 11 , where the generated score is a first score, where the plurality computer-executable instructions further cause the one or more processors to: generate a second score, for the document, that is based on a relevance of the document to a search query; and combine the first and second scores to generate an overall score, where the plurality of computer-executable instructions, which cause the one or more processors to rank the document, further cause the one or more processors to rank the document with regard to the at least one other document based on the overall score.