While writing my review of A Feast For Crows I stumbled across this puzzler:
It's a unauthorized chapter by chapter 'analysis' of A Feast For Crows, available through Amazon as an e-book.
Apparently this guy has written similar unauthorized guides to the Half-Blood Prince and Dan Brown's upcoming book.
This strikes me as questionable.
I haven't seen the text so I can't say how much original material they contain.
But given the recent brou-ha-ha over the Star Wars fan fic sold on Amazon, broken by Lee Goldberg, I have to wonder where the line is.