Most of the biggest systems of all time have produced one or more 10 million selling game. The breakdown is as follows...

1 ten-million-seller
Game Boy Color- Pokemon Gold/Silver
N64- Super Mario 64
PlayStation- Gran Turismo

2 ten-million sellers
SNES- Super Mario World, Super Mario AllStars
Game Boy Advance- Pokemon Ruby/Sapphire, Pokemon Firered/Leafgreen

3 ten-million sellers
NES- Super Mario Bros., Super Mario Bros. 3, Duck Hunt

4 ten-million sellers
PlayStation 2- Gran Turismo 3, Grand Theft Auto 3, Grand Theft Auto: Vice City, Grand Theft Auto: San Andreas

5 ten-million sellers
Game Boy- Tetris, Super Mario Land, Super Mario Land 2, Pokemon Red/Blue/Green, Pokemon Yellow

This brings us to the current systems. With GTA a non-exclusive, its out of the picture. Halo 3 could continue to build on Halo 2's 8 million and counting, and Gran Turismo 5 has a strong chance at 10 million. Wii Sports and Wii Play will blow past the number, and Super Mario Galaxy has some potential. PSP has no shot at a ten-million seller, or anything close.

And then there's DS. Nintendogs has already reached the number, and should climb towards 20 million. New Super Mario Bros. is on the verge of 10 million. Pokemon Diamond/Pearl will obviously cruise past the number.

But then there's a whole slew of other games with a shot at the mark.

Brain Age/Brain Training is close to 8 million, and maintains good sales around the world. In Japan, it continues strong in the top 20 titles two years after release, and should climb beyond 4 million. In the Americas, it's working towards 2 million, and in Europe towards 3 million. If it finds a second wind in America, catching on like it has in Europe, and selling big numbers this holiday season, a climb to 10 million remains possible.

More Brain Training looks like a great candidate. It remains in the top 10 over a year after release in Japan, and could climb to 6 million there alone. If it builds on the success of the first title in NA and Europe like it has in Japan, ten million seems inevitable.

Animal Crossing is selling bonkers in Japan. 5.5 million or more in Japan alone looks likely. And according to recently posted European charts, this title is still charting in the top 10 in some countries over there, too. Doubling the 1.75 million shipped through March to 3.5 is possible, and America has already sold 1.3 million.

Mario Kart DS is maybe the longest shot of currently released games. It has shipped over 2 million units to each Japan, NA and "others," though, and maintains fairly strong sales around the world. 3 to 3.5 million in each of those three major regions could just maybe do it.

And then there's Pokemon again. We know there will be a third game a la Yellow, Crystal and Emerald, but that's a long shot for 10 million. There could be another "remake" like Firered/Leafgreen. Again, a long shot. And a full-blown 5th iteration is also a long shot, likely to be held off until DS2. But DS will have a long life and Pokemon is having a resurgence of popularity in Japan.

So most of these are long shots, in fact. More Brain Training is the only one I'd put at 75% probability, and Animal Crossing the only other one at 50%. But the fact that I can list so many titles with ANY chance of reaching ten million, on top of the 3 you can already pencil in, when it took Game Boy nearly 10 years to produce 5 such games, is rather amazing. We're less than 3 years in on this system, after all. And what about the next 3 or 4 years? Can Nintendo create another social phenomenom IP for DS like they've done several times already? Will they do a Nintendogs spin-off like Nintencats, Nintenllamas, or Nintenrobots, or continue the Brain Age franchise on DS?

How many different games can Nintendo put across the mark, and from how many different IPs???

But Nintendogs counts all the different Nintendogs games together? I think that's a bit unfair.

They are almost completely content-identical, from my understanding. Given how far beyond 10 million sales are going, I think we can count on the fact that there's 10 million unique buyers, just like we can with Pokemon.

Nintencats sounds the most likely, but Nintendo is smart. Nintenpokemon??? That would be really interesting if they did do it. Am I giving them too much credit again?

Interesting you say that.... remember on the Wii's 'Everyone Votes' channel, where they ask what you prefer 'Cats or Dogs?'... I think they were fishing for any marketing info with that idea in mind

Granted, content-wise they are about the same, but IMHO breaking them up would be like breaking up the sales numbers on the PSP and DS based on the case color (which I'm sure both Nintendo and Sony keep tabs on). 

No way Gran Turismo is selling more than 10 millions. Hell, they may not be even that amounts of consoles sold for the next 1-2 years. I think you could have mentionad some almost 10 million selleres, such as Goldeneye, FFVII and I think FFX ( that game deserved it, best turn-based RPG ever)