Harald Edens: Weather Photography http://www.weather-photography.com ... If interested in weather photography this is a wonderful starting point - the links page will take you on to all the major sites.
Underwater photography http://www.underwaterphotography.com This site is worth going to for some of the technical material although you have to subscribe and pay for some of the more detailed material. The entries submitted for the different competitions include some quite extraordinarily beautiful examples.
Wildlife Photographer of the Year competition http://www.nhm.ac.uk ... Wildlife photography competition with exhibition at the Natural History Museum, London
Mathias Klum - Swedish nature photographer http://www.klum.se ... I particularly like his rather abstract water series
