Ben Tesch is about to launch a collaborative weather site called cumul.us. It'll aggregate weather information and harness the wisdom of crowds to see if they can make better weather predictions than the experts.
Will this all work? Who knows, but it only took me two months to make, and I wanted to find out.
Unlike so many other types of information, the web has had little impact on how weather reporting is done (the Weather Channel stuff is still rudimentary), so it'll be interesting to see if this works.