I will throw in my 2 cents of a few books that I have read recently and think others might enjoy as well:
Catch-22 by Joseph Heller - I do want to point out straight away that this book does heavily touch upon the subject of war but, nonetheless, a very enjoyable read for anyone who likes the darker side of humor.
The Stranger by Albert Camus - A rather different novel, since it's exploring a philosophical idea but it certainly doesn't feel that way. I would highly suggest this book to anyone who wants to look at life and the very essence of existence differently.
Slaughterhouse-five; Cat's Cradle; Breakfast of Champions - all by Kurt Vonnegut - I found all of these books thoroughly enjoyable. Vonnegut has an unique and entertaining writing style that I think many will find refreshing.
The Picture of Dorian Gray by Oscar Wilde - Anyone who enjoys clever dialogues will certainly enjoy any work by Oscar Wilde.
Right now I'm lazily going through
The Grapes of Wrath by John Steinbeck and it's a bit too early to put a stamp of approval on it, but I will add to this list later on. I hope some of my suggestions will be useful to you guys!