Dune - my favorite fiction book, hands down. To science fiction what Lord of the Rings is to fantasy.

Brave New World - an excellent complement to Nineteen Eighty-Four. Oppression thru pleasure instead of pain.

Flatland - a quick read about both politics and mathematics. Great way to introduce your brain to a higher plane of thinking about the physical universe.

Jennifer Government - a capitalist dystopia. A well-written response to the myriad socialist dystopias.

Freedom From Fear - a collection of Aung Sang Suu Kyi's speeches and essays. The second part especially is filled with astute insights into democracy and freedom. The eponymous speech is brilliant.

Starship Troopers - nothing like the movie! A Heinlein Juvenile, it has some fascinating political ideas related to the military; a quick read.

Anansi Boys - concerns how mythology and stories shape humanity; great humanist fiction. Really, you could replace this with any Neil Gaiman book. They’re all about life and culture and stories and humanity.

Structure and Interpretation of Computer Programs - if you’re not a software engineer or mathematician, this is probably of no interest to you. If you are, it is revolutionary, ground-breaking, life-altering. It will completely change the way you think. Especially if you were taught in the Object Oriented and Imperative style that 95% of universities teach these days.

The Heart of Aces - indie fiction by and about asexuals. The writing is unprofessional, but enlightening if you want to learn about asexuality from those who are. Edifying, if you’re into that kind of thing.

I’ll leave you with my Amazon lists, if you like: Nonfiction - probably the most interesting list to you. Lots of stuff that sounds intellectually stimulating. Professional - mostly software engineering, but a many are more generic, like business and typography. Fiction - some sound intellectually stimulating, others just entertaining. It’s hit-or-miss. Religion - I mostly identify as Progressive Christian these days; the less you share that ideology, the less interesting you’ll find these.