I have at least 20 wii games right now, including all of the popular ones mentioned above. I can't believe Excite Truck doesn't get more love -- sure, it was a launch game, but it is one of the most fun games I've played in a long time. Maybe I'm not a casual Wii owner.
Sadly, I also got a DS in November or so, picked up 10 or 11 games for it, and then decided never to play them. So I've got about 11 nearly-unplayed DS games, including NSMB and Phantom Hour Glass.