Picked up Brain Age for the Nintendo DS the other night. It’s interesting – not so much a game as different activities that are supposed to be workouts for your brain, and make its “age” younger.
No idea if it has the stated effect, but if you like quick little brainteaser activities or minigames like the WarioWare games, you might be interested.
It also has a version of the newly popular Sudoku, if you’re into that (I prefer to play Sudoku on my Windows Mobile Phone).
For $19 bucks, though, you can’t really go wrong.