Sword Codes
On the Pause Screen enter the following code:

Up, Down, Up, Down, Left, Right, Left, Right, Circle, Square, Circle and Square Unlocks Swordfish Weapon
Left, Left, Right, Right, Circle Square, Square, Circle, Up, Down Unlock Baby Toy Hammer
At the pause menu press Left, Right, Left, Right, Circle, Square, Circle, Circle, Square, Square Unlock Telephone of Sorrow
up, up, down, down, left, right, left, right, circle, square, circle, square Secondary weapon becomes a chainsaw

Unlockables
Do the following to get the following rewards:
Unlockable How to Unlock
Video Gallery Complete the Game
Deactivate 1 Sand Gate 4th Sand Tank
Deactivate 2 Sand Gates 100 Sand Credits
Deactivate 3 Sand Gates Eye of the Storm Time Power
Deactivate 4 Sand Gates 5th sand Tank
Deactivate 5 Sand Gates 150 Sand Credits
Deactivate 6 Sand Gates Winds of Sand Attack
Deactivate 7 Sand Gates 6th Sand Tank
Deactivate 8 Sand Gates 200 Sand Credits
Deactivate all 9 Sand Gates Sand Storm Attack

Sound Credits
This occurs during your second Dark Prince transormation while in the courtyard immediately before a chariot race. In the corner of the courtyard, there will be a hole in the ceiling that respawns enemies until you leave the area. (Near the panel you need to stab and hang from to open the gate) Climb the closest pole to the hole in the ceiling and a female voice will start announcing sound credits for the game.

Gain abilities early
Defeat all of the enemies around a Sand Gate and gain the ability (or Sand Credits) from it . Die right afterward by either falling to your death or having a guard kill you. Retry after getting a game over, and proceed through the segment again. When you stab the Sand Gate again youll get the reward for the NEXT Fountain instead of the reward you're supposed to get. This is a great way to get all of the abilities and Sand Credits early on in the game.