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 avatar and saved the world. Is there a season 3 in the making? atau 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 avatar now that there are spirits in the physical world. It will also focus lebih on the Earth kingdom (yay! lebih Lin Bei Fong). The 4th book will focus lebih on the api nation. There hasn't been an announced released tanggal yet for season 3.

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