Over time, leather shoes tend to get creases in them where you bend your foot. Left for too long, these creases can make the shoe pretty ugly. To keep this from happening, Instructables user "bjagne jr" suggests steaming the shoe with an iron.
We're all well aware that you can iron out wrinkles in clothes, but done properly it can work on leather shoes as well. Basically, you pack the shoes with paper so they hold their form, cover the shoes with a wet cotton cloth, then steam iron the shoes. Once the shoes cool, those wrinkles and creases should be long gone. Head over to Instructables for the full guide.
How to Uncrease Your Sneakers!! [Instructables]