The Ultimate Hitchhiker's Guide to the Galaxy by one of my all-time favorite authors, Douglas Adams, is sheer genius.
Filled with hilarious twists and turns as the universe forces itself upon Arthur Dent, this is a fun-filled novel that you probably shouldn't read in public due to the danger of laughing out loud.
If you haven't read this yet, don't panic, you still have time.
Pick up The Ultimate Hitchhiker's Guide to the Galaxy and you'll own the entire 5 book series. You won't want to stop reading. In fact when you're done you're most likely to immediately read it again.