Well, you can make chocolate-bran flake balls. Or you can make Bran Flake Cookies--we use a recipe from The Not Strictly Vegetarian Cookbook. (Like oatmeal cookies.)
But I made Bran Flake Muffins. These are the basic version, but I think they'd work well with sour milk or thinned yogurt, and only 1 tsp. baking powder plus 1/2 tsp. baking soda. I doubled this recipe and added raisins to only one half.
1 3/4 cups flour (I used whole wheat)
3/4 cup bran flakes cereal
1/2 cup white or brown sugar
2 tsp. baking powder
1/2 tsp. salt
1/4 to 1/2 cup oil
1 cup milk, more or less (can be part fruit juice)
Raisins or other dried fruit, optional
Combine dry and wet ingredients separately, then combine gently. Bake at 375 degrees for about 20 minutes. The final texture depends somewhat on how wet you get the batter. The first panful I made came out fairly dry and solid, but still pretty good; to the rest of the batter in the bowl (with the raisins), I added a bit of extra milk, and I think that was an improvement.
If you want a bit of a stronger flavour, you could add some molasses.