Avatarded

The plot to the movie, "Avatar," revolves around the acquisition of the ridiculously named, "Unobtainum." The bad guys in the movie will do anything to get it, even commit genocide. At the end of the day, it's just a floating rock, which isn't particularly useful when the human species has already mastered interplanetary travel. Instead, they should have paid more attention to another discovery made on Pandora: Immortality.
There's two instances in the movie where they attempt to permanently transfer the consciousness between humans and their Pandoran Avatars. The first fails perhaps because the woman involved is too close to death. After the second and successful transfer, there'd be no reason not to continue experimenting. After all, Avatars are bigger, better and stronger than their human counterparts. If the technique works, then any human with a few million to spend on an Avatar could take a trip to Pandora and become virtually immortal. There's no reason why you couldn't continue and keep transferring from body to body as each one gets old and worn out. You could live forever as long as the infrastructure was in place.
The planet itself seems to be a storage bank for every soul who ever lived on it's surface and was connected to it. That means that even in death you could possibly upload yourself into a new Avatar.
There's no explanation as to what powers this strange phenomenon. It could be the very Unobtanium they're digging up.They're probably wasting it all on hover boards when they could be making themselves Gods.
The other thing is: If Unobtanium floats and the motherlode is under the tree where the Pandoran tribe lives, why hasn't it broken free and floated off during the last few millenia? Mining a floating rock couldn't be particularly difficult. Any earthquake or volcano probably blasts the stuff up into the atmosphere, where it could easily be picked up. Also: There's floating mountains in the movie, which are undoubtably full of Unobtanium. Why aren't they digging up those instead of going to war with Pandora? You wouldn't even have to land the spaceship to fill up your hull. You could just swoop down and scoop it up. The only thing holding those rocks in place during that once scene were some vines.