10. A computer system, comprising: memory; one or more processors; one or more programs stored in the memory and configured for execution by the one or more processors, the one or more programs including: instructions for receiving a search request from a user of the computer, the search request including a plurality of search keywords; and in response to the search request: instructions for identifying multiple resource identifiers in accordance with a first set of predefined criteria for selecting a respective document that satisfies user-specified search keywords from a user, each resource identifier corresponding to a document at a respective data source; instructions for retrieving a document from the respective document source for at least one of the resource identifiers; instructions for identifying within the retrieved document a chunk by applying a second set of user-specified criteria to one or more candidate chunks within the retrieved document; and instructions for providing the identified chunk and a link to the identified chunk within the document for display to the user, wherein the first set of predefined criteria requires that at least a first subset of the search keywords be found within an identified respective document, and the second set of predefined criteria requires that at least a second subset of the search keywords be found within an identified chunk.
14. The computer system of claim 10 , further comprising: instructions for retrieving the corresponding document from the respective document source for at least one of the resource identifiers; instructions for identifying within the retrieved document that no chunk satisfies each of the search keywords; and instructions for displaying a link to search for chunks that satisfy any of the search keywords within the document.