Spyro the Dragon Demo:
At the Main Menu quickly press Up,Up, Down, Down, Left, Right, Left, Right, Square.

Bonus Level 31:
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 to be transported to level 31.

Bonus Level 32:
Go to Level 11 and take the yellow gem ride. Continue 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 above bonus levels, to get a 100% rating. The relics that are collected must be at least gold or platinum. Now 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.