The "SD as Carts" thing got me thinking a while back....
The Virtual Console games that we download likely aren't running on an emulator that's part of the Wii's firmware -- it's likely that they are self contained "applications" unto themselves. Statically linked to the emulators, if you will.
Now, given that 32-128M SD cards are functionally free when compared to an average product's advertising budget, what you could do is (assuming permission from N):
* Find a game house or engine that specializes in creating small, simple games
* Create a small, simple SNES/N64 caliber game *as* an advertisement
* Distribute in magazines/mass mailings/store kiosks this game on the SD card
There are enough small game houses that have experience making GBA and mobile games that a custom made 3-4 level arcade game promoting your product could cost $20,000 or so. Which is a fraction of a modern marketing budget.
Screw advertisements *in* games, make the game the entire advertisement.
(I'm not looking at this from the PoV of a player, as these games would prolly suck, but from the point of view of a marketer.)