If it isn't too cold, I usually wear my Black Diamond Powerstretch gloves. They're simply a polartech glove with a leather palm. They cut the wind a bit and they're warm wen wet.
When those cease to cut it, I wear my BD ice gloves. These are much bulkier than single layer gloves, but thinner than comparable skiing gloves and they will keep your hands warm to about -20F. Originally designed for ice climbing, they are really good at keeping your hands dexterous and warm, (you can't be dropping equipment when climbing).
I found that when it's really cold, it's possible to shoot with mittens on. I use a 20D and can still handle all of the buttons and dials if I need to. The lens caps and hoods are a pain, but you can work around it. Just a little practice is all it takes.
I shy away from chemical warmers. I keep a couple in my pack for emergencies, but haven't needed them. Relying on them for your warmth could get dangerous when they run out.
Colorado David - Have you looked at plastic mountain boots? They work on a principle similar to ski boots, with a shell and an inner insulated layer. The only difference is that they don't suck to hike/climb in (much). Some brands I can think of are Lowa, Koflach, Vasque, Scarpa and La Sportiva. Expensive yes,but they're available used for much less, and it beats frostbite.