I've purchased 90% of my gear from these 3 outfitters. Adventure 16 is great for long distance hiking. They carry real backpacking-specific gear, plus I like the vibe there. REI has great gear, and is helping to sponsor my PCT hike by providing some gear at cost. Finally, Bass Pro Shops have good "keeping warm and dry" gear and a large variety. Although I love the Campmor catalog and read it cover to cover each time a new one arrives, I have yet to buy anything from them.
I prefer Kelty's gear for many reasons, half of them sentimental. My pack is a 12 year-old Kelty Moraine. It fits well and compares favorably to most other internal frame packs, weighing in at just over 3 lbs. I also use a Kelty Dart tent, about 2.5 lbs. and a Kelty 3D Light Year bag, also about 2.5 lbs.
The Kelty Dart is wonderful except for one thing. You can't sit up. If it's raining and you want to put your shoes on before you go out, it could take up to 10 minutes and you might even sprain something. Aside from that, it's great.
TENT UPDATE: December 2003 

I got a new tent. It's the North Face "Pebble" and it weighs about 5 pounds with rainfly, 3.5 without. Now I can sit up. Further updates as I use it.

 
The Kelty 3D is only a 30 degree bag, so I wear my fleece layer to sleep if it's really cold. If it's warm, there's a foot vent with a zipper. I got the extra long so it's really roomy. 
I have some foot/leg problems from an accident many years ago, and have tried several different brands of shoes, some with modifications. My all-around favorite for hiking is the New Balance 805. Lightweight, good balance, good traction, flexible sole. 

Here's one of my favorite gear additions: a Garmin Geko GPS. I used map & compass on my last section hike, and misplaced the trail once or twice. With GPS, map & compass, I'm feeling pretty invincible. The accuracy is amazing. I can walk in a 10 foot circle and my little walking guy on the screen walks a little circle too. There's a bit of the 'big brother' element, knowing that your government can watch you turn little circles in your yard. From space. Pretty wild.
My sons gave me this Sony Cybershot camera for my birthday. It weighs 4 ounces with batteries. I have a 128 MB card for it, so I can take about 250 hi-res pictures without stopping to download them. Most of the hiking pictures here were taken with this camera.
PUR Hiker water filter. Lightweight, easy to use. I just read about someone using an inline automotive fuel filter as a pre-filter, to get out the really big floaties that can clog a filter. I might try that as well, but I've had no clogging problems so far. (Update: I didn't add the fuel filter and have had 700+ miles of trouble-free drinking.)
This is my all-around foul weather gear. I got it on sale at REI, and it works great! It weighs an amazing 7 ounces, is fleece lined, and has elastic around all the openings to keep wind out. I've worn it while hiking at night in a cold, wind-driven rain, and stayed warm & dry. With this over a t-shirt and under my fleece, I could probably sleep on ice. (& wake up really cold.)

These are Op Skimmers. I looked at a lot of different options for stream crossings, campshoes, sandals, etc. These are the perfect all purpose shoe. They're basically intended for kayaking and surfing, but have enough tread to hike in (when I have to cross the same stream 5 times in 1/2 a mile) and slip on & off quickly for use around camp.
Tin Can Stove Man  made me one of his famous stoves. He does not charge a fee, but asks that you spread the word about homemade stoves. Great guy. Mine is made from soda cans, and weighs about an ounce. Using gasline antifreeze as fuel, it will boil water in just a couple of minutes.
This is a bear can. It's about 8" x 12", and has no handles or indentations for Yogi or Boo-Boo to grab onto. It's required in the High Sierras, and recommended in a few other places as well. The problem: It's 8" x 12" of hard plastic, weighs almost 3 pounds and completely dictates how you pack your pack. I may switch to an external frame pack for the Sierras, purely to accommodate this can.
Here's a great illustration of how to pack a pack. It's generally pretty helpful, but where do you put a bear canister? It throws off that nice boxlike compartmentalization they have going on. This is my latest challenge - trying to figure out how to carry my bear can without something hitting me in the head or the butt as I walk. 

Monache Meadows Panorama.