Currently, I have a DS Lite, a Wii, a Game Boy Advance SP - which is gathering dust somewhere - and a special edition Pikachu N64!!! (Unfortunately, this is also gathering dust somewhere else.) And my Mac, if that counts. I play SimCity 4 on it intermittently, so I guess it does. I've also had a GameCube and pretty much every variation of Game Boy, but they've been donated/given away/thrown away over the years.
In the future, I'd like to have a 3DS (i.e. when it reeeeeeally goes down in price) and maybe a Wii U, but I could easily live without the latter. The former I just need for Mario Kart 7, which looks AMAZING!