Developer website: Yahoo!
Yahoo! Local Traffic is a widget for real-time traffic from Yahoo! Local that alerts you to traffic and construction incidents that may effect your ability to get from Point A to Point B. To recieve real time traffic updates directly from Yahoo! Local, simply set your location (City, State or Zip Code) and both the radius and severity level for the traffic information you are most interested in and know immediately about any road delays.
Mac OS X 10.4 or later