Animaniacs and Tiny Toons are definitely nostalgic for me. I have yet to watch the reboot of Animaniacs, but I hear it's pretty good.
If we're counting anime, too, then the first season of Pokemon. Whenever I watch the first episode, I get catapulted back in time to when I was nine, sitting in front of the tv with the VHS box in front of me, thinking "This show is the coolest! Nothing can beat it!"
The very next year, the Digimon anime aired and that became the coolest show, but Pokemon was also still cool.
That's right, I was the kid who liked both monster-catching shows!