The rite of passage ceremony was powerful when they all joined arms. That captures becoming one-of-the people better than anything I have seen.
I also loved the healing ceremony when the clan swayed back and forth. How awesome and selfless to have the whole clan focused on healing someone. Anyone up for some healing circles?
There are reports and numerous posts that people were depressed about not being able experience being part of "the Na'vi." (see link). On the site Avatar forums the topic, "Ways to cope with the depression the dream of Pandora as being intangible" accumulated over 1000 posts. I admit I was sad when I had to "leave Pandora" when the movie ended.
Although some see this as Utopian and even pathetic, I would argue that it has to shows that people are hungry for the elements depicted in Avatar that we have lost in our culture.
And perhaps the ideas are not intangible, but rather need to be adapted to our culture. Instead of being depressed or sad, maybe we should do something about creating some of those elements in our world. Avatar could inspire us to find our connection with the earth and each other. Then it doesn't have to be just a cool movie.