Live Weather On the Web

Oct/06: Online weather information has progressed a long way. (BoatinginCanada.com: Canadian Marine Weather)
Canada: Environment Canada has created the terrific Canadian weather radar images showing current, and animated radar maps across the country. You can easily see if a rainstorm is imminent or 3 hours away. Together with free email forecasts, weather services have never been better.
U.S.A.: The National Oceanic and Atmospheric Administration (NOAA) Earth System Research Laboratory (ESRL) has a project with Aimee Weber Studio in Second Life (due to open in mid November). This features a three dimensional visualization of current weather on display at the Science Center.
World: Google Earth is a broadband, 3D application (free download) showing maps from any angle with custom overlays. Type in your address and fly from space to your house. Request directions and it "drives" there as if you were in a low-flying plane. Awesome. A few overlays you can add: Canadian Weather Links, Google Earth , Google Earth Cloud overlay , Google Earth Radar overlay, Google Earth Blog, CBS Seismic Monitor
real-time (must have Google Earth), USCG Earthquake monitor , Visible Shipwrecks (GE forum)