"What is the book that changed your life? (not novels or religious texts)"
I think it's a wonderful way to connect in a less superficial way and learn a little more about each other. It's also a wonderful way to discover new books worth reading.
This is one of them (the full list is here):
Since its first appearance in 1962, the impact of The Gutenberg Galaxy has been felt around the world. It gave us the concept of the global village; that phrase has now been translated, along with the rest of the book, into twelve languages, from Japanese to Serbo-Croat. It helped establish Marshall McLuhan as the original 'media guru.'