1. A computer-implemented method for ranking search results, comprising: recording anchor text properties from a network, wherein the anchor text properties correspond to a source document and a target document on the network; generating an anchor text index that associates each target document with a term included in the anchor text, wherein the anchor text index is separate from a content index; accessing the anchor text index to determine quantities associated with the anchor text of a particular target document in the index; and using the anchor text quantities to adjust a scoring function that is used to rank the documents for producing the search results.