Slaughterhouse-5 by Kurt Vonnegut

Cat's Cradle by Kurt Vonnegut

Catch 22 by Joseph Heller

Post Office by Charles Bukowski

On The Road by Jack Kerouac

Stranger in a Strange Land by Robert A. Heinlein

Nineteen Eighty-Four by George Orwell

Catcher In The Rye by J. D. Salinger

Pale Blue Dot by Carl Sagan

The Metamorphosis of Prime Intellect by Roger Williams (read it for free online)

Hitchhiker's Guide To The Galaxy by Douglas Adams

Industrial Society and Its Future by Theodore Kaczynski