Unlock Bonus level:
Collect the hidden K, O, N, and G letters in a level to unlock a bonus level.
Successfully complete the bonus level in a world to get a Rare Orb.
Unlock World 9:
Collect all eight Rare Orbs to unlock World 9, "The Golden Temple".
Three Extra lives:
Resume a game from a save with a Wiimote with a low battery. Cranky will warn that your battery is low and award you extra lives to help you out.