Free shipping to U.S. zip codes is part of the deal at Filter Connection, a huge source of camera filters.
Bogen makes some of the best tripods and tripod heads around. Some Gitzo and Manfrotta gear here, too. On this site you’ll also find Gossen meters and Metz flashes, all used by professionals.
Some articles on camera bags and other equipment are listed at Camera Bag Articles24x7.
Camera Traders Ltd. is a site where you can buy and sell used equipment. Most major brands are featured.
Check out the eBay auction site for great deals on anything photographic (and much more, too!). Great source, but when buying anything privately, buyer beware.
Gitzo tripods are among the best tripods made. Their durability is legendary.
Kirk Enterprises offers durable, professional-quality lens mounts, tripods and other accessories.
Lowepro. Manufacturer of fine camera backpacks, photographers’ vests, and more.
Manuals2Go features manuals for cameras, accessories and printers.
Porter’s Cameras features great deals and great prices on over 4500 items related to photography.
Really Right Stuff. Sometimes gizmos like flash arms, clamps, knobs, ball heads and more can make the difference between an easy or frustrating photographic experience. They also make some of the best tripods in the world, lightweight and easy to use.
Slik tripods are of fairly good quality and reasonably priced.
Tamrac backpacking cases come in many shapes and sizes.
Tenba is another source of great camera bags.
Tokina lenses, Hoya and Kenko telephoto and macro accessories are at this site.
Upstrap straps. I have one of these non-slip straps. They really work.
The Vested Interest features custom-made photographers’ vests. Expensive, but worthwhile if you need your gear handy and don’t want to haul a big camera bag.
Vortex Media. Do you do a lot of work in bad weather? Then these camera protection systems may be for you.
Wimberly makes some elegant gimbal-type tripod heads that greatly ease use of long lenses. Some other well thought out equipment is here, too, such as the Plamp, perfect for steadying flowers for macro photography.
Calumet has long been a leader in high-quality view cameras. Now they sell lots of gear from many manufacturers.
Used Camera Buyer. Want to sell some old equipment? Take a look at this source.