as referenced by Radiohead......do you know where your towel is?

The Hitchhikers Guide to the Galaxy - Douglas Addams
If you work in the world of computers, as I used to, you will soon realize that every programmer has not only read this book but has actually committed large portions of it to memory. Considering the abnormally high geek-factor that reading this book might imply (see also: Trekkie, Tron, Firefly, Buffy the Vampire Slayer and UFO Conventions) it is actually very entertaining.

Despite what that may say for my sense of good taste, or my "nerd-hood", I'm sticking with my favorable opinion for at least three reasons. One: The dialogue is utterly stunning if you happen to enjoy British comedy (as I do), Two: Satire, pure and simple. There is nothing sacrosanct in this book (or the other 4 in the "trilogy", or five if you include The Salmon of Doubt) Three: Depressed droids, happy doors, talking books, a fish you put in your ear, characters named Slartybartfast and the occasional appearance of Elvis make for very enjoyable reading. Which brings us down to what the book is best suited for; reading out loud. This is a perfect car trip book, so once you've finished that last Harry Potter, Christopher Moore, or Terry Pratchett book pick this up and have a chuckle.
Rating: A+ for entertainment, B-ish for literary merit
Related:
Any other fiction by Adams


Also somewhat less well done, but still funny is The Starship Titanic, by Terry Jones (Monty Python-er) which is a novelisation of a Douglas Adams video game, which is also interesting....

He also wrote at least one piece of non-fiction worth reading:Last Chance to See - which is a journey around the world in search of nearly extinct creatures, very funny, and sad - not to mention environmentally admirable.