Spectacular Spiderman (I actually preferred this to the 90's series. the story lines were original and dark, Josh Keaton was a great Spidey, the action was solid, and the animationwas WONDERFUL. Ultimate Spiderman can go eat a dick.)
Arrested Development (The only thing I remember about this show (I watched it with my mom when I was like 8 or 10) is that it was HILARIOUS.)
The Grim Adventures of Billy and Mandy (a great show that pushed the limits for kids shows. It was gross, violent, nonsensical, and I loved every minute of it.)
Ed, Edd, 'n Eddy (although it DID go out on one hell of a bang with the Big Picture Show and all)
Who Wants To Be A Superhero (it was a reality show that was actually about being a good person, two things that aren't allowed to mix....)
King of the Hill (I've been watching re-runs on [AS] and it kicks ass. I also saw the last episode. Yeah, it kinda sucked...)
anything on Toonami (never watched it too much as a kid, except for DBZ. would totally watch the hell out of it now)
Samurai Jack (same as Toonami, never watched too much, but what little I did see was awesome)
Double Dare (the best game show EVER. But knowing Nickelodeon nowadays, they'd try to pussify it someway... The slime is green... so it'd have to be an eco-friendly game show? idk, it'd be something stupid if they brought it back now...)
Batman The Animated Series (what else can I say, it's one of, possibly THE, BEST animated show EVER.)
Animaniacs (close second to Batman)
Looney Toons (they're bringing it back, but I'm on the fence about it... one one hand, Bugs Bunny is effing PURPLE, Witch Hazel is now Witch Lezah, and Lola is basically Luanne from King of the Hill, if she were COMPLETELY braindead... on the other hand, it has Kristen Wiig, Fred Armisen, Maurice LaMarche, Jim Cummings, Rob Paulsen, Frank Welker, and Billy West in it.... sooooo.... yeah, it could go either way...)