One of my favourite news sites, Chipwrapper (http://www.chipwrapper.co.uk/), now offers an option to search for articles within a specified time period. Chipwrapper is a Google custom search engine that covers UK news sources on the Internet. Until now, a drawback of the service has been the absence of an option to limit your search by date. You can include a year and/or month in your search but now there are built in options to search for articles published within the past 24 hours, week, month or year.
My earlier review of this excellent service can be found at http://www.rba.co.uk/wordpress/2007/12/29/chipwrapper-search-uk-newspapers/