Some of my favorites:

Slaughterhouse Five by Kurt Vonnegut
I hope they serve beer in Hell (never laughed so hard while reading a book)

On flying (both non-fiction) - back when men where men, used slide rules, had mustaches and we put a man on the moon :-)

Fighter Pilot (Robin Olds) (WWII-Vietnam)
When Thunder Rolled (Ed Rasimus) (100 missions in an F-105 in Vietnam)

Other non-fiction:
Bill Bryson's a Short History of Nearly everything (Slower read, but very interesting)
Skunk Works by Ben Rich (On the SR-71 and F-117)

For fiction, if you like dark humor check out:
Chuck Palahnuik
Tom Robbins
Christopher Moore

And if you're really looking to geek it up two good physics books...

The Amazing Story of Quantum Mechanics by James Kakalios (A lot of good stuff on everything from transistors, to nuclear fission, lasers etc... easier to read than you'd think).

The Fabric of the Cosmos: Space, Time and the Fabric of Reality by Brian Greene (He has a few books out, but this is more on the recent developments in Cosmology, on everything from extra dimensions, black holes, relativity and all that stuff - he is good with analogies and it is easier to follow).