Jake's boyish bliss as he finds out that he can walk and run in his Avatar body.
The entire Na'vi tribe joining hands during Jake's initiation ceremony.
Jake and Neytiri at the Tree of Souls, just before the battle
...then afterwards, with Neytiri holding Jake's human body
Neytiri treats Jake's "feinting", and indeed the entire nature of his human/Avatar duality, more as a medical condition than anything else. The other Na'vi question whether he even counts as a person, and she's just like "dude falls down sometimes. Deal with it."