1. A system comprising: at least one user device that includes at least one processor and at least one computer-readable storage medium having stored thereon computer-executable instructions that, when loaded into the processor and executed, cause the processor to present a user interface enabling each of a plurality of users of an online document library to associate share permissions to various ones of one or more documents uploaded to an online document repository, each share permission specifying a type for an uploaded document, and the share permissions collectively defining a plurality of search scopes of the uploaded documents, wherein each search scope specifies a subset of the uploaded documents for occurrences of at least one user-specified search term; present within the user interface a plurality of ranking devices, wherein the ranking devices are responsive to user activation to indicate ranking preferences for increasing or decreasing a rank of search results identified in a given search scope, the ranking devices controlling display of documents shown in the search results by rank according to the document type; receive representations of the at least one search term through the user interface; receive at least one selection from a user through the user interface that specifies the search scopes; receive the ranking preferences through the ranking devices; and send a search request to the online document repository, wherein the search request includes representations of a user identifier associated with the user, representations of the search term, the ranking preferences, and representations of the plurality of search scopes; and a dynamic indexing and search system operating as the online document repository, wherein the search system includes at least a further processor and at least a further computer-readable storage medium having stored thereon computer-executable instructions that, when loaded into the further processor and executed, cause the further processor to receive the search request from the user device; extract the user identifier, the search term, the ranking preferences, and the representations of the plurality of search scopes from the search request; filter the documents contained within the document repository based on the user identifier and the search scopes; search the filtered documents for any occurrences of the search term to generate search results; rank the search results in the plurality of search scopes based on the ranking preferences; and return ranked search results containing representations of any occurrences of the search term within the filtered documents.
1. A system comprising: at least one user device that includes at least one processor and at least one computer-readable storage medium having stored thereon computer-executable instructions that, when loaded into the processor and executed, cause the processor to present a user interface enabling each of a plurality of users of an online document library to associate share permissions to various ones of one or more documents uploaded to an online document repository, each share permission specifying a type for an uploaded document, and the share permissions collectively defining a plurality of search scopes of the uploaded documents, wherein each search scope specifies a subset of the uploaded documents for occurrences of at least one user-specified search term; present within the user interface a plurality of ranking devices, wherein the ranking devices are responsive to user activation to indicate ranking preferences for increasing or decreasing a rank of search results identified in a given search scope, the ranking devices controlling display of documents shown in the search results by rank according to the document type; receive representations of the at least one search term through the user interface; receive at least one selection from a user through the user interface that specifies the search scopes; receive the ranking preferences through the ranking devices; and send a search request to the online document repository, wherein the search request includes representations of a user identifier associated with the user, representations of the search term, the ranking preferences, and representations of the plurality of search scopes; and a dynamic indexing and search system operating as the online document repository, wherein the search system includes at least a further processor and at least a further computer-readable storage medium having stored thereon computer-executable instructions that, when loaded into the further processor and executed, cause the further processor to receive the search request from the user device; extract the user identifier, the search term, the ranking preferences, and the representations of the plurality of search scopes from the search request; filter the documents contained within the document repository based on the user identifier and the search scopes; search the filtered documents for any occurrences of the search term to generate search results; rank the search results in the plurality of search scopes based on the ranking preferences; and return ranked search results containing representations of any occurrences of the search term within the filtered documents. 5. The system of claim 1 in which the document types include one of document owner, shared on a restricted basis, or shared on a public basis.