An Interactive Website

An idea I had about an interactive site using JavaScript to keep track of "real time" information came out of the cross-country road trips I frequently take. A centralized, up-to-date traffic site would be fantastic; I envision the site encompassing all of the interstates in the US, as well as the scenic bypasses and major arteries in various cities across the nation. I'm not entirely sure HOW this could be done, but I think it would be a fabulously useful tool. I know the state of Colorado has a site (the DOT site for the state, I believe) that updates on weather closures, but I'm thinking beyond that -- traffic accidents, regular rush-hour snarls, and what not. This would be very useful not only for the traveler, but for those locals who are caught in rush hour and need to find a way through.