I mainly use NOAA and ADDS which is the aviation section of the NOAA site. One product I learned of here at sailnet is the "Hourly Weather Graph" which is great for sailors (and pilots) because it shows an hourly forecast of when and how the winds are expected to clock throughout the day among other weather conditions. With knowledge of that, you can compare to the actual conditions to determine if the weather is changing faster, slower or exactly as predictedwhich can be handy.
Another cool product is the "Forecast Discussion" which is essentially the forecasters thoughts on the forecast he's published. It gives great insight to how they were thinking, how the output of the different weather forecast models differ and their confidence in the forecast. They often also reveal the sense of humor of the real life person that has to create the forecast products we use.
s/v Palmetto Moon
1991 Catalina 36