Some of my favorite and most visited sites and vendors.
Nikon USA http://www.nikonusa.com/en/index.page
Nikonians http://www.nikonians.org/
Nikon Café http://www.nikoncafe.com/vforums/index.php
Canon USA http://usa.canon.com/cusa/consumer/products/cameras
Information on Canon cameras, lenses, and photographic accessories.
Canon Digital Photography Forums http://photography-on-the.net/forum/index.php
An international discussion forum about photography, gear and techniques. While concentrating on Canon equipment, all are welcome to join the discussion and share tips and knowledge.
Fred Miranda Photography Forum http://www.fredmiranda.com/
Another international discussion forum focusing on photography, gear and techniques.
Think Tank Photo http://www.thinktankphoto.com/
Manufacturer of photography bags and accessories.
B&H Photo and Video http://www.bhphotovideo.com/
One of the largest and best photo/video stores in the world.
The Luminous Landscape http://www.luminous-landscape.com/index.shtml
Comprehensive site devoted to the art of landscape and nature photography.
LensRentals.com http://www.lensrentals.com/
Camera and lens rental company featuring an excellent photography blog on the site.