Gah, I can't pick just five!
Oh well, my favorites in no particular order:
1. Avatar: The Last Airbender ( It's almost impossible to not like this show)
2. Code Lyoko ( anyone remember this?)
3. Xiaolin Showdown ( It's nice to see this on other people's lists here:) )
4. Storm Hawks ( Awesome show that all of my friends have seem to forgotten)
5. Invader Zim ( It used to creep me out when I was younger, though now I like it. )
Honorable mentions go to Ed, Edd, & Eddy, Courage the Cowardly Dog, Foster's Home for Imaginary Friends, Teen Titans, Dexter's Labratory, Grim Adventures of Billy & Mandy, Powerpuff Girls, Pokemon, Tom & Jerry, Fairly Oddparents, Angry Beavers, Codename: Kids Next Door, Jackie Chan Adventures, Static Shock, Totally Spies, American Dragon: Jake Long, Danny Phantom, Kim Possible, Class of 3000, CatDog, Hey Arnold, and all those other awesome shows around that time:)