If you have not seen this already, check out the Bing Maps Traffic Gadget.
It attaches to your Windows Vista sidebar and shows the real-time traffic conditions from Bing Maps for the major city around the U.S. of your choice. The cities you can choose from include:
Atlanta, Boston, Chicago, Denver, Detroit, Houston, Los Angeles, Milwaukee, New York, Oklahoma City, Philadelphia, Phoenix, Pittsburgh, Portland, Providence, Sacramento, Salt Lake City, San Diego, San Francisco, Seattle, St. Louis, Tampa, and Washington D.C.
Here are some screenshots of the gadget:
The Red on the map indicates a traffic speed of 0-25 mph. The Yellow indicates traffic speed of 25-45 mph. The Green indicates a traffic speed of 45+ mph.
The gadget also provides easy shortcuts to the Search, Driving Directions, and Traffic features at Bing Maps. If you hover over the map, the shortcut buttons appear on the left.
Here's a screenshot of the real-time Traffic feature at Bing Maps: