Did you know there's not a single shoehorn instructable? I just had to make one. Really, you've got to believe me, the Robot made me do it. This one is made from a spoon and a few hundred hammer strikes. It’s actually more useful than I though it would be.
A shoehorn (sometimes called a shoespooner) is a tool that lets the user put on a shoe more easily. It does so by keeping the shoe open and by providing a smooth surface for the foot and the heel to move, without crushing the shoe's counter (the vertical portion of the shoe that wraps around the back of the foot), in this way acting as a first class lever. - Wikipedia
Update: There actually was a single shoehorn instructable.