Lamma Consorzio, italian forecast very accurate : http://www.lamma.rete.toscana.it/mare/modelli/vento-e-mare
For local needs, windguru provides very liable informations
Link to Windguru in english : http://www.windguru.cz/fr/index.php?sc=767&switchlang=1
Weather Online provides very liable informations all around the world : http://www.weatheronline.co.uk/
You must click on 10m Wind (Mitteleur.) to see the maps.
Very interesting website from the Royal Yachting Association : http://www.rya.org.uk/Pages/Home.aspx
It is a real pleasure for us to sail with a smartphone as we knew sextant navigation before. This app is really a revolution for those who sail a lot on different boats.