I'll only focus on series and not include movies, I'll also strictly stick to childhood stuff and not include my teenage years or I'd still be typing tomorrow.

Here are some series that I enjoyed, some I've even been rather obsessed with when I was little.
Teenage Mutant Ninja Turtles
Extreme Dinosaurs
Street Sharks
Spider-Man
Pinky and the Brain
Darkwing Duck
Timon & Pumbaa
Ganbare, Kickers!
Dragon Ball
Dragon Ball Z
Pokemon
Digimon
One Piece
Ranma 1/2
Crayon Shin-chan
Max Steel
Yu-Gi-Oh!
Beyblade
Alvin and the Chipmunks
What's with Andy?

I was pretty much destined to grow up into a geek x?D