Otherpower.com - The Alternative Energy site that inspired us to get into wind power. Check out the Discussion Forum.
Wondermagnet.com - Sells high power Neodymium magnets
Windstuffnow.com - A great site with many interesting projects. Ed sells the Blade Designer program that we use.
Hugh Piggott - UK wind power guru. Get his book, Wind Power Workshop
OP IRC Users Web Directory - From the OP IRC channel, a listing of participants who have their own project pages.