This would actually just be a list of less well known but still popular books.

Probably 90+% of books published are "obscure" in the sense that they didn't become best sellers and won't be recognized by the average person or likely mentioned in a list like you requested. Most books just don't become popular enough to be well known. Which I think is a tough benchmark.

"Lost Continents" by L. Sprague de Camp (1954). Looks at Atlantis and other lost continents as rhetorical devices in ancient history and philosophy, 20th century pseudoscience/pseudohistory, and science fiction

Kybalion, Reality transurfing, The illusion of money, The minimalist entrepreneur, Power vs Force, Psycho cybernetics, No self no problem

thanks for actually responding to the question!

By definition such a list is impossible

Give dirth of publications, don't think there's enough time for even all of the Noone's[0] to review even a fraction of what's available.

In today's day & age more difficult for unpublished prints and/or pre-electronic distribution pre-prints to "be unknown" / "be obscure".

Claude Shannon references to unpublished works : https://findingaids.loc.gov/exist_collections/ead3pdf/mss/20...

[0] : Noone coat of arms : https://coadb.com/surnames/noone-arms.html

Anything by Merwin Crawford Young, early Zen Buddhist texts, Anthony Giddens, Peter Berger, the Tao te Ching, Max Weber, Norbert Elias, Nisargadatta Maharaj