With World War Z now in theaters, Titan Books has released a making-of companion book called "World War Z: The Art of the Film" which includes the script as well as a ton of concept art.
In the film, the zombies don't get a lot of close-up face time. There's some stuff, but mostly we see the undead in wide shots, as a swarm of decaying, scrambling bodies. The companion book goes deep and sheds some light on some terrific concept pieces featuring the zombies and ShockTillYouDrop.com has compiled a few images which you can check out here.
In related news, The Hollywood Reporter says that Paramount and Brad Pitt will actively turn to developing a sequel after the film's $111.8 million worldwide opening this weekend. The movie earned $66 million domestically and $45.8 million overseas. It was made for $190 million.