i've been reading the Warlord of Mars comics from Dynamite. there is also a Dejah Thoris series that is pretty good and takes place before John Carter arrives on Mars/Barsoom.
Marvel has an upcoming serries of books that will directly adapt Burrough's John Carter
i wasn't aware of that. i'll def check it out. i had hoped that the movie coming out next year would spark interest in the books. more comics are always good too.