I have used fleece to make rag quilts, I only use 2 pieces, it really doesn't need a middle piece, it's warm enough, and I sew the 2 pieces together with an X, just like you would do if you were using flannel. Even though fleece doesn't "rag", it still looks great. Fleece does stretch in one direction more than the other so be sure all your pieces are cut and sewed with the stretch all going in the same direction.
Here are pictures of fleece rag quilts I have made.
http://www.quiltingboard.com/t-76618-1.htm