The Walking Dead is a comic series (also published in TPB collecting 6 issues at a go) which is excellent and well worth reading. It tells the story of a group of people trying to survive in a world overrun by zombies, basically it starts up where most movies end.

World War Z by Max Brooks is also quite interesting. It's a book made up of short stories from a selection of survivors of a recent worldwide zombie outbreak. The stories are compiled by an official who is writing a report on behalf of the UN. It is an interesting read and makes you think of how governments would deal with any major global pandemic, be it zombie or just a deadly illness.

Other than that I can't say that I have really read a lot of Zombie books.