So I just finished watching season 2 of Legend of Korra, and I'm certainly not done. I realize she basically did her job as अवतार and saved the world. Is there a season 3 in the making? या a whole new series of a new Avatar?

Yes. Nickelodeon has ordered season 3 and 4.
Season 3 is called "Changes" and will deal with how Korra handles being अवतार now that there are spirits in the physical world. It will also focus और on the Earth kingdom (yay! और Lin Bei Fong). The 4th book will focus और on the आग nation. There hasn't been an announced released तारीख, दिनांक yet for season 3.

Season 3 is playing right now! New episodes every Friday!