Let me get straight to the point. If the Earth was unexpectedly destroyed in a thermonuclear / asteroidal / zombie undead armageddon, and if only one remnant of human civilisation could be shot in to space to be found by aliens millions of years in the future, it would have to be William Gibson's Neuromancer.

Those aliens will need to know what humanity was like (even if only to recreate us as a digital slave race in their virtual reality matrix), and if any single author grasps the state of our technological society today it is William Gibson. I was 14 when I first read Neuromancer, one of the first generation to grow up hooked in to the computer-generated realities that Gibson so presciently explores. For me and for millions of others who live in the modern reality of computers and the internet, William Gibson's imagined future is closer to the truth of now than any work of realist literature.