"One who gains strength by overcoming obstacles possesses the only strength which can overcome adversity." - Albert Schweitzer
I read that one a few years ago, and he got some details wrong and one has changed since then, but I've got some that may outrank some of his 15.
In Fed rules at least, you can fumble the ball into the opposing end zone, and if it comes to rest there and nobody plays the loose ball (probably out of ignorance), it's a touchdown.
Also in Fed, if you're knocked out of bounds by an opponent, you can still jump off the ground and play the ball, and it's not dead. So you could knock it back into the field, intentionally or accidentally, and play continues.
You can snap the ball by turning around with it and having a back take it from your hands.
You can pass the ball to yourself.