Gygax + Mearls is probably accurate. So I suppose what we are listing in this thread is "Stuff that I'd put in the list if it were Gygax + Mearls + me."There are just too many to list. I mean, what are the criteria? Fantasy books that are in any way vaguely D&Dish? That would be thousands of novels.
The main charm of the original appendix is that it was Gygax's own - stuff that he said influenced him in creating D&D (and presumably Arneson). I can't remember if Lord of the Rings was in the original appendix, but Gary seemed to have a strange distaste for Tolkien, to the point where he downplayed his influence in a way that spoke of some kind of hang-up with Tolkien on his part. But is this list Gygax + Mearls? Whose influences does it represent?

With regard to Tolkien... it's pretty clear that a) Gary Gygax didn't much like "The Lord of the Rings" (he said as much on multiple occasions), and b) he was surrounded by Tolkien fans who demanded elves'n'dwarves'n'orcs, so elves'n'dwarves'n'orcs they got. Obviously, you can't have elves, dwarves, halflings, half-elves, and half-orcs as five of your seven core races and not acknowledge Tolkien as a major influence on the game! But it's not surprising that Gygax would sound a little defensive about it. In this community, it takes guts to admit not liking LotR, especially for someone as prominent as Gygax.
(I sympathize, since this is a pet peeve of mine, too. I was brought up on "The Lord of the Rings," but the mandatory inclusion of elves'n'dwarves'n'orcs in every freakin' D&D setting grates on me. Tolkien put them in his world because he was Doing Things with them. Each one had a place in his cosmology and a reason for being. In most D&D settings, they're just sort of... there, because, well, Tolkien had 'em so we gotta have 'em too. Okay, rant over.)