Open the Around Apple Map:
In the Crazy Pyramid beat the bottom row (all of the 5's) and you will recieve an around the apple map.

Open the Little Apple Map:
Beat the second row (all of the 4's) and you will receive the little apple map.

Unlock the Bike:
Beat the third (all of the 3's) row and you will recieve the bike (you can use this instead of your taxi).

Unlock the Baby Carriage:
Beat the fourth (all of the 2's) row and you will recive a baby carige (you can use this instead of your taxi).

Open Up S-S Level:
Beat 1-1 in the Crazy Pyramid.

Original Characters:
Beat the sixth row mini-game (S-S) in Crazy Pyramid mode to unlock all four original characters (Axel, Gena, B.D. Joe, Gus) from the first Crazy Taxi.

Disable Arrow Indicators:
At the character selection screen, hold Start and press A. If you entered the code correctly, the message "No Arrows" will appear in the lower left corner.

Expert Mode:
At the character selection screen, hold Start + Y and press A. If you entered the code correctly, the word "Expert" will appear in the lower left corner. No stop or arrow indicators will appear in this mode.

Alternate Display:
During a game, press B on controller three to switch the display to a first person perspective. Press Y on controller three to change to another camera angle. Press X on controller three to view a speedometer. Press A on controller three to reset the display. Press L on controller three to change the arrow color.

Disable Destination Indicator:
At the character selection screen appears, hold Y and press A. If you entered the code correctly, the message "No Destination Mark" will appear in the lower left corner.

Expert Mode:
At the character selection screen appears, hold Start + Y and press A. If you entered the code correctly, the word "Expert" will appear in the lower left corner. No stop or arrow indicators will appear in this mode

Thanks to Revolution readers Rsayo, spyduck, Angewomon and damaster!