I don't know if I really even believe in the idea of "must read" books, but here are at least a few I highly recommend. In no particular order.
FICTION
The Mysterious Island - Verne
The Time Machine - Wells
Nineteen Eighty-Four - Orwell
Fahrenheit 451 - Bradbury
Brave New World - Huxley
Snow Crash - Stephenson
The Shockwave Rider - Brunner
The Fountainhead - Rand
Cryptonomicon - Stephenson
The Foundation trilogy - Asimov
Something Wicked This Way Comes - Bradbury
Strangers - Koontz
After Dark - Murakami
It - King
The Lord of the Rings - Tolkien
The Hobbit - Tolkien
Perdido Street Station - Miéville
Permutation City - Egan
Glasshouse - Stross
NON-FICTION
Report from Engine Co 82 - Smith
Godel, Escher, Bach - Hofstadter
How the Mind Works - Pinker
The Four Steps to the Epiphany - Blank
Charles Proteus Steinmetz: The Electrical Wizard of Schenectady - Bly
Hackers: Heroes of the Computer Revolution - Levy
Artificial Life - Levy
Cyberpunk: Outlaws and Hackers on the Computer Frontier - Haffner & Markoff (Note: this book is not without controvery. There is a lot of debate about the veracity of much of the material on Mitnick. However, it is a wildly entertaining read, and an introduction to a number of interesting characters. But I'd suggest following up by reading other related titles, especially regarding Kevin Mitnick)
Ghost in the Wires - Mitnick (Mitnick's autogiography, basically)
Takedown - Shimomura & Markoff
The Fugitive Game - Littman (of the books written about Mitnick, but not by Mitnick, this one has a reputation for being a little more "pro Kevin" whereas a couple of the others are sort of pointedly "anti Kevin" in their bias. Maybe it all balances out in the end if you read them all).
The Cyberthief & the Samurai - Goodell
The Cuckoo's Egg - Stoll
How To Create A Mind - Kurzweil
On Intelligence - Hawkins
Engineering General Intelligence (volumes 1 & 2) - Goertzel
The Hidden Pattern - Goertzel
Everything and More: A Compact History of Infinity - Wallace