Thought I would start this and see what people have to contribute:
Fleece/pile clothing:
Ever wonder how to keep your pile clothing new feeling and soft? Add a shot of Murplyhey's Oil Soap into the wash when you wash your pile stuff.
Warmer feet in winter:
Wear a thin pair of liner socks, nylon or other synthetic, under your heavier socks. Also douse your feet with a spray on antiperspirant.
Another warmer feet trick is to wear a pair of gaiters, the full length size. These hold in the heat to your lower legs and do a really good job of keeping your feet warm.
Warmer hands:
Take a couple of those heat packs and stick them in the back of your gloves. They will warm the blood flowing into your hands.
Warmer everything:
Take a couple of the stick on heat packs and put one over each kidney. You will be surprised how much warmer your body will get.
Cold weather camping:
Heat up a bunch of water before you crawl into your sleeping bag at night. Pour it into some good water bottle and toss one into the bottom of the sleeping bag.