Looney Tunes Captain Kangaroo more Looney Tunes Electric Company more Looney Tunes Great Space Coaster Hot Fudge (regional show) oh, and Looney Tunes (old Daffy Duck was the awesomest - the ones where he was insane)
Phineas & Ferb Fanboy & Chum-Chum Kick Buttowski of course, SpongeBob (my child watches a bunch of others, but these are the only ones I actively pay attention to)
EDIT: Oh, and Starrcade (the video game show, not NWA wrestling) was a Saturday morning staple
As a parent of a four-year-old, I am regularly exposed to Nick Jr. programming (mostly The Wonder Pets!, Max and Ruby, The Fresh Beat Band, and The Backyardigans. Fortunately Offspring doesn't have much of a taste for Dora, because I can't stand that shit.).
As for when I was a kid: Sesame Street, The Electric Company, Tom & Jerry, Looney Tunes, Laff-a-Lympics, Super Friends, Wonderama, and Spider-Man.
"The object of persecution is persecution. The object of torture is torture. The object of power is power. Now do you begin to understand me?"
http://www.youtube.com/watch?v=I8TkIPNWczo The package wasn't as awesome as I remembered it from a decade ago, but I still would love to know who did that song (the version in the video, not the original).