When bananas are on sale or on the reduced produce shelf....I buy them! Peel them, cut them into smaller chunks and freeze....perfect for smoothies.
Use half of a mashed ripe banana to replace an egg in recipes like muffins...as long as you don't mind a little banana taste (use a little baking powder).
I have also used banana to replace oil in certain recipes...like you use applesauce. Go Bananas!!.