Barley flour may be substituted for all or part of wheat flour in recipes. However, due to its low-gluten content, you may wish to combine with a high-gluten flour when using it for baked goods intended to rise, such as breads and cakes.
You could try flatbreads or tortillas maybe using a combination of the flours.
you can make good pancakes using a combo of flours. I have used millet with buckwheat and sorghum before. I bet millet and barley together would make good pancakes. Just use a regular pancake recipe and use half of each kind of flour instead of the wheat. Soak as usual and make the pancakes!