If you haven't already noticed, weather.com has a new weather map in beta and it's very slick. Imagine GoogleMaps, with all its click-and-drag/scrollwheel zoom goodness with weather overlayed.
You can choose clouds and/or RADAR images with transparency, add roads, and animate. The interface is smooth like butter. I still prefer Accuweather overall, but Weather.com scores points here.
Weather Radar and Weather Maps - weather.com