You've got to check this one out – especially if you live in Chicago, where they say "If you don't like the weather, wait five minutes."
Head on over to http://www.weather.com, enter your local zip code, and click on the "New Radar Map" link.
At first you'll see a traditional radar map display. And, so you're thinking – big deal – weather map – seen it before. Well, click to interact, and now you can overlay road info and zoom into street level if you want – and what I like the most, intuitively click and drag to move around the map.