I am really enjoying the animated series Avatar: The Last Airbender. This cartoon, which was launched in 2005 and wrapped up earlier this year (for a total of 3 seasons), is outstanding. It appeals to all ages, and is a joy to watch. Here's a brief premise, as taken from Wikipedia:

Avatar: The Last Airbender takes place in a fantasy world that is home to humans, fantastic animals, and spirits. Human civilization is divided into four nations: the Water Tribes, the Earth Kingdom, the Air Nomads, and the Fire Nation. Each nation has its own natural element, on which it bases its society. Within each nation exists an order called "Benders" who have the ability to manipulate the eponymous element of their nation. The show’s creators assigned each Bending art its own style of martial arts, causing it to inherit the advantages and weaknesses of the martial arts it was assigned. The Bending types are Waterbending, Earthbending, Firebending, and Airbending.

The Avatar is the one person who is able to bend all four elements. He (or she) serves to ensure that the nations all live together in peace. One hundred years before the starting point of the series, Aang, a young airbender, learns that he is the next incarnation of the Avatar (each generation yields one Avatar to preside over the nations). He disappears out of fear of his looming responsibility. With the Avatar gone, the Fire Nation attacks the others, and essentially takes complete control.

As the series begins, two water nation siblings, Sokka and Katara, happen to find the Avatar frozen in a block of ice. They remove him from the ice, along with his giant flying bison Appa, quickly become friends, and set out to help the Avatar master the four elements, so that he may restore balance and order to the world.

I'm currently half-way through the second season, and I'm greatly anticipating the rest. The overall story-arc is wonderful, and each episode also has a great side story. Action scenes are incredible, the animation is fantastic, and the dialogue is very funny. I highly recommend this series to anyone even remotely interested in animated series' (or good television for that matter). I'm really looking forward to finishing out this season and the next!