Cartoons now adays are lame. The golden years of cartoons was the 90s. Anyone who wants to watch some quality cartoons should be looking on the boomerang channel.
As far as awesome cartoons.
Animaniacs,
rugrats,
johnny bravo ( I think someone already said that)
Looney tunes.
Tiny toons,
and teenage mutant ninja turtles.
Elfen Lied, Trigun, Fullmetal Alchemist, Fullmetal Alchemist Brotherhood, Hellsing, Fooly Cooly, Gurren Lagann, and the anime movie Princess Mononoke are all good. Most anime haters haven't seen good anime.
the best: Dragon Ball Kai (it's a remake of Z), Code Geass, Evangelion (the new movies are the epic), Soul Eater, Gurren Lagann, FullMetal (old and new one), Death Note, Cowboy Bebop, GTO and Zetsubou Sensei.
American ones: Family Guy and everything from Seth Macfarlane (like American Dad, Clevelan show) and South Park