All Final Fantasies from V-XII + T have at least one extremely cheap way of getting through the game. Mind you, some come much later than others. I'm sure you all know what they are.

Other than that, the R.Y.N.O. from Ratchet and Clank, The Patriot from MGS3, the Fireball from New Super Mario Bros., and the Draw Hidden Skill from Zelda Twilight Princess.