Harry Potter and the Half-Blood Prince Cheats (Wii)

Collecting the Crests hidden around Hogwarts unlocks the following rewards: 

3 Crests - Two Player Dueling Pack 1: Draco & Luna

8 Crests - More health in duels

14 Crests - Two Player Dueling Pack 2: Training Ground Dueling Arena

21 Crests - Dungbombs in prank boxes around Hogwarts

29 Crests - Two Player Dueling Pack 2: Crabbe & Goyle

38 Crests - Score boost in flying events

48 Crests - Exploding Cauldrons in prank boxes around Hogwarts

59 Crests - Two Player Dueling Pack 4: The Transfiguration Dueling Arena

71 Crests - Max health in duels

84 Crests - Two Player Dueling Pack 5: Ginny & Hermione

98 Crests - Love Potion in Potions Club

113 Crests - Two Player Dueling Pack 4: Paved Courtyard Dueling Arena

129 Crests - More mini-crests with each cast