Reader Goldfarb pointed us to Call Me Joe, a novella written in 1957 by Golden Age science fiction writer Poul Anderson. Many fans of Anderson suspect that the story was an important influence on Avatar, and some are calling for Anderson to be credited on the film. And it's easy to see why.
Like Avatar, Call Me Joe centers on a paraplegic — Ed Anglesey — who telepathically connects with an artificially created life form in order to explore a harsh planet (in this case, Jupiter). Anglesey, like Avatar's Jake Sully, revels in the freedom and strength of his artificial created body, battles predators on the surface of Jupiter, and gradually goes native as he spends more time connected to his artificial body.
http://io9.com/5390226/did-james-cameron-rip-off-poul-andersons-novella