Some of the mixes we took on vacation to Grandma's house: Two bread mixes, a pizza crust mix, a pancake mix, and a Chocolate Chip Cookie mix.
I make a lot of GF mixes to save time and make my baking simpler. I usually mix up a big batch of the Bread Flour Mix A from Annalise Roberts "Gluten Free Baking Classics" and then make a half dozen or so bread mixes that I can keep on hand. I just line up a half dozen containers with lids, and then measure each dry ingredient (except for the yeast) into my containers assembly-line style. (I use powdered milk in my baking so I actually measure in the dry equivalent of the milk, and then just add warm water instead of milk when I mix it up. In my case 3 T. of milk powder equals 3/4 c. of milk.) When you have all your ingredients in put the lids on tight and shake it up. If you don't shake it well and mix all your dry ingredients up, you get dry powdery lumps (probably from the sugar or gelatin). One of the nice things about her bread recipe is that she uses the same dry ingredients for sandwich bread, hamburgerand hot dog buns and dinner rolls, so I can use my bread mixes to make several different baked goods.
My strategy for other baked goods is this: Whenever I bake something that I don't already have a mix on hand for I have made a habit of making a couple of mixes along side my recipe. That way the next couple of times I bake that recipe, I won't have to bother mixing up the dry ingredients. You can make any mix, by combining your dry ingredients (except for yeast) in a container that can be sealed airtight, or a zipper-style plastic bag. Make sure you shake it up well, and label it.