I can't believe no one has mentioned a small pressure cooker! Trust me, pinto beans won't cook in several hours at the Grand Canyon North Rim! A 3qt model will come up to pressure quicker with less heat and works well for me. My favorites are the EU stainless models but, a cheap aluminum model from India work well for ~$20USD.
For skillets, I tend to favor steel crepe pans or french fry pans. Lighter weight is nice even in the trunk of a car and, less mass means they heat faster on a normal camp fire. That being said, I'm happy with a cast iron skillet but, one of the double pans/skillets where the lid doubles as a griddle works well or, a double pan like the chicken cooker. Lastly, an enameled Dutch Oven finishes the cookware set with something to make acidic stews or breads with.