I have two seconded recommendations:
The Integral Trees by Larry Niven. In fact, a lot of the N-Space books (his fictional universe) are good, such as
Ringworld.
Donaldson's Thomas Covenant books. I actually think
Lord Foul's Bane, the first in the series, is the best one.
Here's a few of my favs:
Nonfiction:
Guns, Germs, and Steel: The Fates of Human Societies by Jared Diamond. This book is to history what Freakonomics is to economics. And honestly, it's a better book
"Surely You're Joking, Mr. Feynman!": Adventures of a Curious Character. This is an edited compilation of Richard Feynman's memoirs.
The equation that couldn't be solved : how mathematical genius discovered the language of symmetry by Mario Livio. Long title, awesome book.
The Tipping Point: How Little Things Can Make a Big Difference by Malcolm Gladwell. I found myself not agreeing with his conclusions, but he makes his case so eloquently that this book was hard for me to put down.
Fiction:
The Terror by Dan Simmons. Fictional account of the loss of the HMS Erebus and HMS Terror, which went missing while trying to find the Northwest Passage in 1845 or so. This is a "historical horror" novel (my invented term!). There's a creature, and isolation, and lots of bad food.
Hyperion by Dan Simmons. My favorite book by Simmons. He's such a good author, his work merits two entries on my list. This one is a soft scifi space opera that is organized like Chaucer's Canterbury Tales. It tells the story of pilgrims on a space ship bound for the planet Hyperion. Like most of Simmons' work, it's a mashup of horror, scifi, and intertextuality.
Watership Down by Richard Adams. I adore this book. I've reread it more times in my life than any other book. It's just ... a classic.
Preludes and Nocturnes by Neil Gaiman. Okay, this is a graphic novel. And yes, I'm a 40-something dude who reads comic books. But seriously, read Gaiman's Sandman graphic novels, of which this is the first, and tell me that this isn't a serious art form.
The Anubis Gates by Tim Powers. A body-hopping werewolf, the Egyptian underworld, time travel, and a bit of romance.
Jumper by Steven Gould. Ignore the excrementitious film version of this book. It's a great read.
Cryptonomicon by Neal Stephenson. A fantastic, fictionalized ride through history following the role that cryptography plays in deciding the outcome of wars and individual human lives.
Artemis Fowl by Eoin Colfer. Tired of that goody twoshoes Harry Potter? Ever wonder what Stewie from Family Guy would be like if he were rich and kidnapped elves? Well, read this book.
The Call of Cthulhu by H.P. Lovecraft. I'm a Lovecraft-o-phile. Some would say
At The Mountains of Madness is his best work. They would be wrong. This short story, which is arguably the definitive work of "wierd fiction", has been eating the souls nerds like myself for decades. Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn!
"I am made from the dust of the stars, and the oceans flow in my veins ..." ~Sir Neil
