Na'vi Photoshop Tutorials

I've been doing a little bit of searching. These are a few of my favorites. The first is definitely the most in-depth.

http://www.webdesign.org/photoshop/photo-editing/angelina-jolie-as-a-na-vi-from-avatar-movie.18062.html

http://www.naviblue.com/hometree/forums/13-Avatar-Fan-Made/61961-Avatar-Tutorial-!#61961

http://www.webdesign.org/photoshop/photo-editing/na-vi-avatar-photo-manipulation-exclusive-tutorial.18015.html

And here's a fabulous video by mateo785 of his process. Note, it is not a complete tutorial because there a lots of steps left out, but for an experienced hand, it's a great reference and inspiration.