1. A computer system for processing information about documents in a collection of linked documents, the system comprising: one or more processors; and memory storing one or more programs, the one or more programs including instructions for: crawling at least a subset of the documents in the collection of linked documents; extracting, from the crawled subset of the documents in the collection of linked documents, information concerning a plurality of outbound links between documents in the collection of linked documents; generating an anchor map based on the information extracted from the collection of linked documents that concerns the plurality of outbound links between documents in the collection of linked documents, wherein the anchor map comprises a plurality of anchor records, and wherein a respective anchor record of the plurality of anchor records identifies: (A) a respective target document, wherein the respective target document is pointed to by one or more outbound links among the plurality of outbound links, (B) a list of inbound links identifying a set of source documents in the collection of linked documents that contain the one or more outbound links to the respective target document, and (C) a list of annotations corresponding to the respective target document, wherein a respective annotation in the list of annotations includes a text passage extracted from a respective source document of the set of source documents that is determined from text of the respective source document, and wherein the text passage is within a predetermined distance of a respective outbound link, from among the one or more outbound links pointing to the respective target document, in the respective source document that points to the respective target document; processing at least a subset of the plurality of anchor records, including, for each anchor record in the subset of the plurality of anchor records, adding to a document index entries for terms in the list of annotations in the anchor record, wherein the entries correspond to the target document identified by the anchor record.