Historically, my favorite thing to make with overripe bananas is muffins - I use the banana bread recipe from the red & white cookbook, substitute half whole wheat flour, add mini chocolate chips, and bake in a muffin pan. They are wonderful, especially shortly after they are done baking. But I make them often enough that they've lost their wow appeal with the kids and I'm always looking for something new to do with expired bananas.
This recipe (once again, from my favorite baking blog) is my new favorite! I've made them with peanut butter chips as originally suggested, but we like them better with chocolate chips. I made a few substitutes to the original recipe: use 1/2 c whole wheat flour, substituted fat-free Greek yogurt for the sour cream and added 1/2 tsp baking powder to the dry ingredients. Remembering to sprinkle extra chips on the tops of the muffins is key! I stretched it out to make 26 muffins, using a large batter scoop for portioning.
These are terrific - moist and chocolatey, and I don't feel guilty sending them for school snack because, hey, bananas!