If you're a parent, like I am, that's into handheld gaming, you might want to check out UFO Interactive's line of Smart Games for kids. This line includes titles such as "Smart Kid's: Gameclub," "Smart Girl's: Playhouse," and "Smart Boy's: Gameroom." Having 3 daughters, I am most familiar with the "Smart Girl's" line of games, but really it's mostly just the art style that's specific to girls. Boys (especially those in the 2 to 6 year old range) would get just as much out of any of the games as would girls, but I can completely understand why you might not prefer to have your son seen playing "Smart Girl's: Magical Book Club."
I know that Nintendo is trying to target the younger kids with a lot of their DS titles, but, from what I've seen, most of the good games start at about age 6. If you have a kid younger than that, there really isn't a whole lot that they can do that will keep their attention and challenge them. I have found the "Smart Girl's" games to be great for my daughters. My 2-year-old is really starting to learn stylus skills (which seem to translate fairly well to mouse skills on the PC). Of course, she can't read, but she has, fairly quickly, learned how to navigate the entire game. There are puzzles, matching games, drawing pages, musical games, etc. that keep her occupied whenever we are out somewhere that she can't run around. My 5-year-old is just starting to outgrow the game a bit, but she still likes to play it, especially if she can show her little sister how to do things. She still plays it, but she has started getting into games with deeper story lines, now that she's learning to read. Still, any of the Smart games will keep the girls occupied and learning whether it be just for a couple minutes or a couple hours. If you have kids in the 2-6 year-old range, I highly recommend that you look into these titles.