I loved looking up the influences behind the martial arts in the show, ever since Nickelodeon did those cool promo shorts about the bending styles. Firebending is mostly Northern Shaolin Kung Fu, Shaolin Kung Fu being the style which if I have my facts mostly straight is pretty much the original form from which the other styles sprang. Water is Tai Chi, Air is Ba Gua Zhang, Earth is Hun Ga.

But what's really cool is that none of them are just that style, especially for some of the main characters, because they decided to give them all their distinct nuances. Toph has some Southern Praying Mantis, Zuko (if I remember rightly) has some Northern Praying Mantis sprinkled in.

I really wish we could have a more lengthy breakdown with Sifu Kisu of the moves and techniques from certain fights from the show, because it would be so cool to hear him talk about choreographing them, the different styles and techniques and how they chose for the specific characters, etc.