Here is an article about 10 possible sources of inspiration for Avatar. It includes a few of the stories and novels mentioned in your post and the comments thread, so I thought you (and your SF-enthusiast readers) would find it interesting:
http://www.darkroastedblend.com/2009/12/10-possible-sources-of-avatar-in.html

Cameron’s own films are somewhat ambiguous on the issue of war — there are strong antiwar themes in many of the films, especially The Abyss and the anti-nuclear war stuff in the Terminator movies, but on the other hand, there’s an appreciation of heroic combat; he scripted the 2nd Rambo movie, and the fighter planes in True Lies were even supplied by the US military; actor Michael Biehn’s roles in Cameron’s films have included both heroic military characters (in T1 and Aliens) and a villainous one (in The Abyss, where his character, a military officer who’s predisposed to view an alien culture as hostile and winds up attacking one that turns out to be friendly, is a clear predecessor for Stephen Lang’s character in Avatar). And Aliens combines a high level of violence and tropes from military science fiction (including some from Starship Troopers) with an overall leftist political view, and a jaundiced view of corporations in particular (“You know, Burke, I don’t know which species is worse. You don’t see them fucking each other over for a goddamn percentage.”), in much the manner of leftist action movies like Robocop and Billy Jack. I found a quote from Cameron that summarizes his views quite nicely (and it’s funny to google this and see how people seem to think that “antiwar” is synonymous with “liberal”, saying that it proves Avatar is “Decidedly Liberal”, “Not Right-Wing Friendly”, and “a Big, Dull, America-Hating, PC Revenge Fantasy”):

“It’s also a move about peace, from a guy who admits to paramilitary impulses. ‘I have an absolute reverence for men who have a sense of duty, courage,’ he said. ‘But I’m also a child of the ’60s. There’s a part of me who wants to put a daisy in the end of the gun barrel. I believe in peace through superior firepower, but on the other hand I abhor the abuse of power and creeping imperialism disguised as patriotism. Some of these things you can’t raise without being called unpatriotic, but I think it’s very patriotic to question a system that needs to be corralled, or it becomes Rome.’”

“‘I can’t go back,’ said Towser.

‘Nor I,’ said Fowler.

‘The would turn me back into a dog,’ said Towser.

‘And me,’ said Fowler, “back into a man.’”

And “Call Me Joe” also uses the device of projection to explore the question of what it really means to be human; the magazine blurb was, “If someone could just work out a definition for the term ‘human being,’ maybe we could decide whether or not Joe really was human, in the end.”

Anyway, I’ve long thought that Simak is very underrated in terms of libertarian themes in his work. “The Big Front Yard” is all about how trade leads to peace. The beginning of “City” is one of the very few science fiction stories (such as Jack Williamson’s “The Equalizer”) that posit that in the future cities would become technologically obsolete, leading to a back-to-the-land return to rural life (and in general, Simak’s stories have a rural quality that’s rare in the genre, influenced by his Midwestern background). And “Empire” is about the struggle to overthrow a tyrannical government whose political power is based on a monopoly over energy production with a cheap and decentralized source of energy.

I would note that Stephan Kinsella also posted a review, specifically from a protect-your-property-rights perspective that was somewhat surprising:

http://blog.mises.org/archives/011295.asp#c647091

http://en.wikipedia.org/wiki/Call_Me_Joe