10 out of 19 for me:
Wii Sports
Wii Play
Super Mario Galaxy
Mario Party 8
The Legend of Zelda: Twilight Princess
Super Paper Mario
Resident Evil 4 Wii: Edition
Mario Strikers Charged
Link's Crossbow Training
Metroid Prime 3: Corruption
I yet have to buy Wii Fit, Super Smash Bros Brawl and Red Steel. My friends have Big Brain Academy, and it rocks, but I don't see the use of buying it when they already have it (it's a party title pur sang!).