A few more (but mostly novels, and all speculative fiction, sorry). And few of these are probably what you really seem to be looking for -- ie something where gender is simply not mentioned, as opposed to something where one or more characters have genders outside the binary or where a deliberately gender-neutral society is being described.
The narrator of Melissa Scott's The Kindly Ones
is never referred to by gendered pronouns.
Part of Marge Piercy's Woman on the Edge of Time
takes place in a post gender maybe-utopia where people are referred to by the pronoun "per".
Barry King's story "Virtual Private Network"
has a first person narrator who is never referred to by any gendered pronouns.
In Nancy Kress' "My Mother, Dancing", the humans use nongendered pronouns (hir, singular they) throughout, and the aliens appear to be actually ungendered. You can read the first part here
There's an interesting short essay by Ursula K. LeGuin about the issues of attempting genderless writing here
A list of apparently non gendered children's books here
. And I think in most of Mo Willem's Elephant and Piggie books, Piggie is not gender defined (though in jacket blurbs and sometimes by clothing Piggie is female).