deeperblue.com is a meeting place and forum for many dedicated and talented free-divers, it is a great place to pick up tips and learn from great experimenters such as Sebastian Murat and Eric Fattah.
His site is http://liquivision.com/eric.php where he sells liquid goggles, nose clips and a free-dive computer designed to his specifications.
http://marine-mari.blogspot.com/ for contact with Mari Kagaya, an incredible veteran dive instructor and dive guide who has miraculous underwater eyes. She is capable of spotting things underwater that can barely be seen with a microscope.
http://apnea.cz/ is a great site for training material, they have really put a lot of work into it also trying to make it that the great untrained don’t log on easily and then drown themselves doing DIY apnea training.
http://www.freedivecentral.com is a site where the focus is definitely on the competitive of free-diving, good for looking up world rankings etc.
www.apnea-total.com/ is probably the busiest free-diving school on Earth, based on the scuba diving and backpacker mecca of Koh Tao in Thailand, it is definitely the best thing to do on the island.
http://yogada.ru/ is a very interesting site for those interested in yoga and the non-competitive side of free-diving, still at the launching stages, in the next few months it should up and running in both Russian and English. The instructors involved are great bunch, excellent teachers and good fun.
http://www.getawaycolombia.com/Home.html A really special place in Colombia offering free-diving and yoga escapes.