As far as I can tell the Windguru site takes information from many computer models and puts it into a plain format, its not actual winds but forecast.
The site is primarily for windsurfers but allows you to add spots anywhere on the planet, yes you read that right anywhere on the planet.
There is also a small download of spots for Google Earth so you can see where other people have created spots near your location.
Last week we did a film shoot in the Cape and as I don't know that area I used a spot already set up for Caledon to check what might happen.
As the job approached the professional forecaster for the film crew, sent his reports and they were flipping close.
Used in conjunction with your other forecasting tools this is a powerful toy.
Oh and best of all, its free, lets hope it stays that way.
Suggestions for other weather sites also gadly taken, then I will add them to the weather tag on the search cloud.