I would at least like to be able to constrain searches according to how old the page is (creation or update, I'd be grateful for anything at this stage). Google advanced search lets you select web pages updated in the last 3 or 6 months prior to the search, but I never saw that selecting that box had any noticeable effect. Nor can I tell if tweaking the URL gets anywhere. The term as_qdr=m3 or as_qdr=m6 appears in the URL, but I can't get it to do anything interesting.