Suggestion ...NOAA, etc.
NOAA for detailed weather information.
http://www.nws.noaa.gov/forecasts/xml/
Library of Congress
http://www.loc.gov/standards/sru/
[Edit] sorry I don't think this the Library of Congress link is valid. I have implemented a "screen scraper" (they don't care but require a 6 second delay between queries) in the past. Is there a generic block for a screen scraper/html -> xml mapper that we could get/have access to?

