Ok, i just rewatched the finale and at the end the music was really really familiar so i was thinking and it sounded like the music from Halo 3's ending. I'll find a youtube vid.
Heres the halo 3 ending i was talking about, wait until after the trumpets. http://youtube.com/watch?v=clt7zsx6aJQ
Now either go to your T.V. and watch the ending part (before the tea shop). Its about at the part where Zuko and Aang are talking, or just sit through this movie:
http://www.livevideo.com/video/SkyBlue952/A5D700C7D25348BC82E9CA876ADB1EB8/avatar-book-3-chapter-18-21-so.aspx
I'm serious please do it.