i have a "Wind" bookmark folder in my firefox bar with all the links from :
http://www.fksa.org/showpost.php?p=26171&postcount=3
I open all in tabs and try to get the best "overall" view of whats projected.
I can say that airnet is pretty accurate. its used by aviators so its gotta be using the best technology/wind info possible.
Obviously no one site should be your one-stop-shopping for this info. Use a combo of many.. also go back and review sites "projections" after a day on the water to get a real feel for accuracy.