Well so far we got:
Wii Sports
Wii Play
Wii Fit
Mario Kart Wii
More than likely Wii Sports Resort, Wii Fit Plus, and New Super Mario Bros Wii will hit it. Brawl has an outside chance of doing it as well.
So what else coudl do it? Well Super Mario Galaxy 2 has a very solid chance. Galaxy 1 is one of the most critically acclaimed game ever and a sequel would definitely benefit from that. Even more so, if Nintendo really put big money into advertising they could get larger first week sales all around. Same could be done with Zelda Wii which also has a solid chance. Now Zelda has never been something to really hit the mainstream all that much (although Ocarina of Time and Twilight Princess (kinda) achieved this. But with a big push they could polarize a lot of buyers to pick it up.
I also think a Nintendogs game would do quite well... having a very well thought out dog simulator could push a lot of copies. Also a full fledged 3D pokemon game would be quite successful as it builds off the brand.
But not really much else that I can see that would push to 10 million in sales from Nintendo although that's quite a bit haha. Nintendo can have a lot of big and successful games with that large userbase it is just they really need to have large focus on advertising and hype.
