Definitely World War Z and The Zombie Survival Guide. Both are zombie books by Max Brooks (rhyme not intended), but each one takes a completely different approach to zombies. World War Z is particularly good, one of my favorite books. Watchmen is great, and it's take on the superhero genre is just as refreshing as World War Z's take on zombies.
As far as fantasy goes, I haven't read much. I do enjoy the Inheritance series (Eragon, Can't Remember the Second Book's Name, Brisingr, and a 4th one is on the way). The second book wasn't anything great, but the first was very good and I loved the third.
If you don't visit the websites, then the book versions of The Darwin Awards and Stuff White People Like are very funny, particularly The Darwin Awards.
This is somewhat off-topic, but what is the rule for book titles? Are you supposed to put quotations around them?
Also consider: 1984, Lord of the Flies, and the Halo novels (particularly those written by Eric Nylund, the best of them being Fall of Reach). Regardless of your opinion of the story in the Halo videogames, the books are excellent, and again, Fall of Reach is especially good.
Finally, I remember greatly enjoying The House of the Scorpion when I was maybe 11 or 12, but I can not be certain it would hold up if I read it today. It may still be worth a look though.