#15 Mario 3: Warp Whistles
As revealed in the Oscar-nominated film, The Wizard, Mario could simply toot his flute (twice!) and he would be brisked away by a Tornado giving him the ability to skip over 90% of the game. The initial trip would take you to the first Warp Zone area, but it limited you to World 4. If you had the second flute on hand, however, you could use it to take you to the last section of the game, World 8. This resulted in many people beating the game without experiencing the majority of what is considered one of the best games ever made.
There are actually three of these flutes, which is shown in the video above.