In my hand at nostalgia, I'm gonna state out mine to be the Game Boy Advance, the Gamecube, and the Sega Genesis.
My very first experience in gaming was with a copy of Sonic Adventure on a Dreamcast my brother had borrowed. I believe that set the pace, and soon enough, I had a nice, large TV in my closet, with the Genesis sitting near it. Oh, the games. Sonic, Bubsy, Jurassic Park, Vectorman, the 6-Pak containing Super Hang-on and Columns, GOD THAT WAS AWESOME.
The GBA came up next, and man, that was sweet. The pearl white original, I had a charging pack to replace the batteries, I had the little light attachment because that screen was crap. Rayman Advance, Super Mario Advance, Castlevania: Circle of the Moon... I loved that thing. Then I ruined it one day trying to clean it and water dribbled through the start button. BOOM. Screen looked like it shattered internally. Got a GBA SP later on, black, scored Pokemon Sapphire with it.
Gamecube was a great one, played the hell out of it, and still have games from when I had it, mostly since the Wii transition meant I didn't need to lose them. Sonic Adventure 2: Battle, Billy Hatcher and the Giant Egg, Viewtiful Joe, Harry Potter: Quidditch World Cup, Pokemon XD: Gale of Darkness, oh the fantastic experiences.
I did also have an N64, where I discovered my one true love: Destruction Derby 64... okay, three true loves. That one, Star Wars Ep.1 Racer, and Majora's Mask.
I also have a PS2 that I got semi-fond with, but it never really picked up nostalgia the same way as the other ones, plus I still religiously play my PS2 ever since I modded it.
I've also brought back my Dreamcast enjoyment, having gotten Dreamshell and an SD reader for more modded fun, though it seems to have become my closest thing to a NES at any rate. Sad that I play more Captain Skyhawk and Solar Jet-man on it than things like Jet Set Radio or Zombie Revenge.
EDIT...
I personally object to the inclusion of the Wii on these lists. The Wii came out only eight years ago, in 2006. Not only that, because of the length of the last console generation, the Wii is still alive, getting a small trickle of releases even still, with several upcoming releases still planned. If it's not even dead yet, I don't think it really qualifies for a list of nostalgic things.
By this logic though, you can't technically refer to a Dreamcast or a PS2 as nostalgic then, because titles are still being made for it. True, they're indie, and the Dreamcast doesn't get that oh-so-public word out, but still, we can't really rely on this sense for nostalgia's sake.