Spyro The Dragon Demo:
At the title screen press Up, Up, Down, Down, Left, Right, Left, Right, Square. 

Eggipus Rex hidden level:
Go to Level 11 and take the yellow gem ride. Then proceed until reaching the area where the huge dinosaur chases Crash.
Allow the second pterodactyl to capture Crash to reach level 32.

105% completion:
Collect all relics and gems, including those from the Hot Cold and Eggipus Rex bonus levels. Then, approach Crash's sister,
next to the save spot, to find another clear gem. Take the gem to view a very nice fireworks display and finish with a 105%
completion status.

Hot Cold Bonus Level:
Go to Level 14 and ride about half way through the level to find alien crossing sign on the left hand side. Run into the sign and
you will be transported to level 31.

Instant Uka Uka:
Press Triangle + Circle + X + Square. Note: This may only be done once per life. 

                                        Game Shark Codes

     99 Lives -
     Note: When, you die, you have to go back to the warp room to replenish your lives.
          d005beecf64c 
          800b5d4c6300 
          d005beecf64c 
          80068f586300 
     Enable All Powers - 80069178003f 
     Have All Gems - 
          80068fb0ffff 
          80068fb2ffff 
          80068fb4ffff 
          80068fb6ff00 
     Have All Sapphires - 
          800691b4ffff 
          800691b6ffff 
          800691b8ffff 
     Have All Crystals - 
          8006912cffff 
          8006912effff 
          80069130ffff