The only thing I know of to use overripe bananas for is banana bread. You can freeze overripe bananas in a baggy until you are ready to make the bread.
Bananas that are riper than what you would want for eating fresh, can be used for making banana bread. Overripe bananas can also be frozen for later use.
The obvious thing is banana bread, but you can also used mashed ripe bananas in variety of baking, such as cakes, cookies or in making banana pudding. They pair well with nuts, or oatmeal.