Enter these codes during gameplay- you must be standing still:

ABYXYBBYBA- 50 Skill Points (beef up your stats, but you still have to level up special skills normally)
AXYBYBXBBA- 100,000 Gold (can use multiple times)
AYXXYYBYXA- God Mode (main character and any ship he's on, doesn't cover sails or crew)
AXYXYBBYBA- Changes Reputation to Neutral