40. The computer readable storage medium of claim 23 , wherein the one or more programs further comprise: instructions for-updating the web crawl interval of a document after retrieving a new copy of the document's content from its host and detecting content changes to the document based on the new copy.
40. The computer readable storage medium of claim 23 , wherein the one or more programs further comprise: instructions for-updating the web crawl interval of a document after retrieving a new copy of the document's content from its host and detecting content changes to the document based on the new copy. 41. The computer readable storage medium of claim 40 , including instructions for updating the web crawl interval of the document to be less than the initial web crawl interval when the document's content has changed, and updating the web crawl interval to be more than the initial web crawl interval when the document's content has not changed.