World War Z by Max Brooks!
The movie missed a huge opportunity and robbed us all by turning this masterpiece into yet another last-man-standing zompocalypse. A sub-genre that is all well and good, don't get me wrong; my favorite movie happens to be 28 Days Later, so I got nothing against the sub-genre. But there are a TON of those kinds of movies. What World War Z does is take the zompocalypse genre and truly explode it into a worldwide sphere, exploring not only the immediate effects on individual people, but also the economic effects, religious change, military innovations and failures, travel and trade issues, and secondary effects on human societies who don't even come up against the zombies at all.
It is seriously amazing. Read. It.