8. A computer system for enabling a user to execute one or more search queries to identify and rank relevant documents from a corpus of citationally-related documents, said computer system comprising: an input interface that enables said user to select a first set of identification information identifying one or more input documents from said corpus of citationally-related documents; a computer-accessible index stored in a computer-readable storage device, said computer-accessible index comprising identification information identifying each potential input document from said corpus of citationally-related documents and, for each said potential input document, identification information identifying a selected number of citationally-related potential output documents from said corpus of citationally-related documents, said computer-accessible index further comprising for each pair of citationally-related potential input document and potential output document a first numerical score configured to have a statistical correlation to whether a direct citation exists between said corresponding pair of citationally-related documents and wherein said first numerical score is calculated based at least in part on how many indirect citations exist between each said pair of citationally related documents and, for each indirect citation, how many citation links separate each said pair of citationally-related documents; a computer processor configured to execute instructions stored in a computer-readable storage device, said instructions configured to cause said computer processor to: use said first set of identification information to ascertain, from said computer-accessible index, a second set of identification information identifying, for each of said one or more input documents, a selected number of citationally-related output documents and, for each pair of citationally-related input document and output document, said first numerical score; and calculate, for each of said citationally-related output documents, a second numerical score configured to have a statistical correlation to whether a direct citation exists between any of said one or more input documents and each of said citationally-related output documents, and wherein said second numerical score is calculated based at least in part on said first numerical score; and an output interface to present search query results comprising a third set of identification information identifying one or more of said citationally-related output documents and wherein said search query results are sorted and displayed in accordance with said second numerical score.
8. A computer system for enabling a user to execute one or more search queries to identify and rank relevant documents from a corpus of citationally-related documents, said computer system comprising: an input interface that enables said user to select a first set of identification information identifying one or more input documents from said corpus of citationally-related documents; a computer-accessible index stored in a computer-readable storage device, said computer-accessible index comprising identification information identifying each potential input document from said corpus of citationally-related documents and, for each said potential input document, identification information identifying a selected number of citationally-related potential output documents from said corpus of citationally-related documents, said computer-accessible index further comprising for each pair of citationally-related potential input document and potential output document a first numerical score configured to have a statistical correlation to whether a direct citation exists between said corresponding pair of citationally-related documents and wherein said first numerical score is calculated based at least in part on how many indirect citations exist between each said pair of citationally related documents and, for each indirect citation, how many citation links separate each said pair of citationally-related documents; a computer processor configured to execute instructions stored in a computer-readable storage device, said instructions configured to cause said computer processor to: use said first set of identification information to ascertain, from said computer-accessible index, a second set of identification information identifying, for each of said one or more input documents, a selected number of citationally-related output documents and, for each pair of citationally-related input document and output document, said first numerical score; and calculate, for each of said citationally-related output documents, a second numerical score configured to have a statistical correlation to whether a direct citation exists between any of said one or more input documents and each of said citationally-related output documents, and wherein said second numerical score is calculated based at least in part on said first numerical score; and an output interface to present search query results comprising a third set of identification information identifying one or more of said citationally-related output documents and wherein said search query results are sorted and displayed in accordance with said second numerical score. 14. The computer system of claim 8 wherein said output presents said search query results in the form of an interactive self-organizing map.