I think this is the first real-time wave height map that has been featured on Google Maps Mania. Meteo Mari e Venti is a Google Map that shows wave and wind height and direction predictions for the Mediterranean Sea.
There are four map views available on Meteo Mari e Venti, wave height and direction, period and wave direction, wind at 10m and wind gusts. Each of the maps show the current weather conditions. You can also view the forecasts for the next 120 hours using the buttons above the map.