I have listed some cheats here.
To enter the cheats, drain the water from the sand
castle in Treasure Trove Cove. Then, enter the sand
castle, and use the Beak-Buster to type in the codes.
Make sure that you type CHEAT, before the actual code
on the "CHEAT" codes list below, or it won't work.

Here are all 7 "CHEAT" codes:

NOWYOUCANFLYHIGHINTHESKY Infinate Red Feathers

BANJOBEGSFORPLENTYOFEGGS Unlimited Eggs

GIVETHEBEARLOTSOFAIR Unlimited air

DONTBEDUMBOGOSEEMUMBO 99 Mumbo Tokens

ANENERGYBARTOGETYOUFAR Large energy bar
Warning: DO NOT use this code if you
have red life blocks! They will change back to yellow
if you do.

LOTSOFGOESWITHMANYBANJOS Unlimited lives

AGOLDENGLOWTOPROTECTBANJO Unlimited Gold Feathers
(This was a code that I submitted to IGN64, which they added,
but only one month later to change my name to someone else's,
with the same code description. . . rip offs!)

For the following codes, you don't need to do type "CHEAT".
You need to find the spell books before doing these codes.

BLUEEGGS Gives you 200 eggs. 200 becomes
max. ammount.

REDFEATHERS Gives you 100 red feathers. 100 becomes
max. amount.

GOLDFEATHERS Gives you 20 gold feathers. 20 becomes
max. amount.

There are still more to come! Check back soon!