In many survival situations, the ability to start a fire can make the difference between living and dying. Fire can fulfill many needs. It can provide warmth and comfort. It not only cooks and preserves food, it also provides warmth in the form of heated food that saves calories our body normally uses to produce body heat. You can use fire to purify water, sterilize bandages, signal for rescue, and provide protection from animals. It can be a psychological boost by providing peace of mind and companionship. You can also use fire to produce tools and weapons. -Excerpt from the US Army Field guide
Usually I stay away from combat resources because they are a bit over the top for bushcraft (for example a 15 inch "survival knife"). However when it comes to creating fire in the worst conditions with minimal equipment, their field manuals are a great resource.
Below are some more great resources, slide presentations by Kevin Estela from the Survival Instructor Wilderness Learning Center in Chateaugay, New York. If you would like to learn more and develop firecraft skills, be sure to join the Firecraft Group