SREHTAEF Doubles the amount of feathers you can hold.
SGGE Doubles the amount of eggs you can hold.
FOORPLLAF You become immune to damage from falling.
KCABYENOH Refill your energy bar gradually after taking damage.
XOBEKUJ Enables the Jukebox in Jolly Roger's Lagoon.
YGGIJTEG Activates the "Jiggy location" signs in Jiggywiggy's Temple.
GNIMOH Get homing eggs.

Here are the codes that even Cheato himself can't give to you...