The Bus

Off the top of my head:

Catch-22 by Joseph Heller
Watership Down by Richard Adams
Stories by T.C. Boyle
Fast Food Nation by Eric Schlosser
In a Sunburned Country by Bill Bryson

RagingBull80

These are absolutely some of my favorites:

Less than Zero - Bret Easton Ellis
American Psycho - Bret Easton Ellis
The Catcher in the Rye - J.D. Salinger
The Stranger - Albert Camus

Honorable mention:

Do Androids Dream of Electric Sheep? - Philip K. Dick
The Siege of Trencher's Farm - Gordon M. Williams
Fear and Loathing in Las Vegas - Hunter S. Thompson
No Country for Old Men - Cormac McCarthy

rkndkn

The Three Musketeers - Alexandre Dumas
Butcher's Moon - Richard Stark
Magic - William Goldman
Swan Song - Robert McCammon
Watchers - Dean Koontz

darkside

1984 - George Orwell
The Catcher in the Rye - J.D. Salinger
Hitchikers Guide to the Galaxy - Douglas Adams
Slaughterhouse Five - Kurt Vonnegut
Running with the Demon - Terry Brooks

Tscott

I'm sure I've posted in a similar thread before but:

Gödel, Esher, Bach: An Eternal Golden Braid - Douglas R. Hofstadter
House of Leaves - Mark Z. Danielewski
Alice in Wonderland/Through the Looking Glass - Lewis Carroll
The Locked Room - Maj Sjowall and Per Wahloo
And since we're listing series as one book: The Sandman - Neil Gaiman

Drop

A Confederacy of Dunces by John Kennedy Toole
Dark Tower IV: Wizard and Glass by Stephen King
The Stranger by Albert Camus
Cat's Cradle By Kurt Vonnegut
A Connecticut Yankee and King Arthur's Court by Mark Twain

Choosing five is ridiculous, there are so many more.

lizard

Hmm, a list like this would change over time, save for the first one:

Pride and Prejudice, by Jane Austen
Trickster's Choice, by Tamora Pierce
Life on the Mississippi, by Mark Twain
Honor Harrington series, by David Weber, if I had to pick just one, I'll just go with the first: On Basilisk Station
Harry Potter series, by J. K. Rowling, if I had to pick just one, I'd choose Harry Potter and the Goblet of Fire

All of the above I've read multiple times. Although I've only read them once each, a couple of memorable books for me years ago were The French Lieutenant's Woman, by John Fowles and Les Misérables, by Victor Hugo.

Honorable Mention:
Sword of Truth series, by Terry Goodkind, if I had to pick one, I'd go with Faith of the Fallen.

I rarely read nonfiction, preferring escapist stuff, but two favorites are Seabiscuit, by
Laura Hillenbrand and The Beak of the Finch, by Jonathan Weiner