15. A non-transitory computer-readable memory device, comprising: one or more instructions, which, when executed by one or more processors, cause the one or more processors to: determine, at a first time, a first position of a document with respect to a first set of documents in a first list of search results, the first position being based on a first score of the document with respect to one or more scores associated with the first set of documents in the first list of search results; determine, at a second time, a second position of the document with respect to a second set of documents in a second list of search results, the second position being based on a second score of the document with respect to one or more scores associated with the second set of documents in the second list of search results; determine an amount or rate of change between the first position and the second position; generate a third score for the document based on the determined amount or rate of change between the first position and the second position; and rank the document against at least one other document based on the third score.
15. A non-transitory computer-readable memory device, comprising: one or more instructions, which, when executed by one or more processors, cause the one or more processors to: determine, at a first time, a first position of a document with respect to a first set of documents in a first list of search results, the first position being based on a first score of the document with respect to one or more scores associated with the first set of documents in the first list of search results; determine, at a second time, a second position of the document with respect to a second set of documents in a second list of search results, the second position being based on a second score of the document with respect to one or more scores associated with the second set of documents in the second list of search results; determine an amount or rate of change between the first position and the second position; generate a third score for the document based on the determined amount or rate of change between the first position and the second position; and rank the document against at least one other document based on the third score. 17. The computer-readable memory device of claim 15 , where the one or more instructions to determine the amount or rate of change further cause the one or more processors to: determine a rate at which the document moves between the first position and the second position, and where the one or more instructions to generate the third score for the document further cause the one or more processors to: generate the third score based on the determined rate.