I set up a small book exchange on my property adjacent to the PCT for thru hikers to use as a source for new reading material. It started as an experiment and has now become something that I will continue, as it brings me immense pleasure to touch the people who pass by my place in this way.
You can read all about its genesis here, and the source of some of the books there. In 2017, I themed my hiker oasis for the Thoreau Bicentennial. The theme for 2018 celebrated the 150th anniversary of the arrival of John Muir in California. The theme for 2019 celebrates the bicentennial of the birth of Walt Whitman.
With each re-theming, my Little Free Library offers a slightly different selection of self-printed booklets with works by Thoreau, Muir, and Whitman. In addition to the books, the hiker register that visitors are asked to sign uses a prompt that changes with each year. Both the library contents and the prompt follow the theme for the year.
As a former philosophy professor (and book lover), I enjoy offering something to hikers that is not just the same old, same old — food for the mind, rather than food for the belly. To my knowledge, this is the only library directly on the PCT (or, technically, 50 feet from the PCT). For those into such things, it is Library Charter # 29178 with the organization Little Free Library.