- a world atlas
- a medical encyclopaedia
- The Self-Sufficient Life and How to Live It by Seymour or some such book
- Jules Verne's Mysterious Island
Those are the only 4 books I actually own that I would save.

I'm gonna take the Sheldon approach here & say I'll keep every work ever written backed up to a high density flash drive.

I Ching - Wilhelm Translation
Tao Te Ching - Gia-Fu Feng Translation
Sun Tzu - Denma Translation
Yoga Sutras of Pantanjali
King James

I absolutely do not travel without my I Ching. If I could take only one thing with me... the I Ching travels before underwear.

Sri Oracle

• A survival guide - Resist the elements
  
• Sun Tzu's Art of War - Fend off other tribes
  
• Adam Smith's Wealth of Nations - Rebuild the economy
  
• Plato's Republic - Replace with political ideology of choice
  
• The Zombie Survial Guide - Replace with book appropriate to your specific apocalypse.
  
  

Originally posted by Silcone Synapse
There are so many amazing books noted in this thread,
I have only one to add.

It is called "The long walk",by Slavomir Rawicz.

It took a while but I did eventually get that book you recommended. A great read and I howled like a baby when Katarina died in the desert.

Surprised to read Mr Rawicz ended up a teacher in a Nottingham school, AND that he and his friends spotted a couple of yetis whilst hiding in the mountains. Detailed sketch and description too, but that deserves a different thread.
Whole story has been called a hoax but that's based on paperwork/records that are highly likely to be fraudulent anyway.