David Chalmers recently put up a constellation of zombie-related links; while the zombie simulator is, admittedly, pretty cool, be sure to check out Max Brooks' (Mel Brooks' son, not surprisingly) rather slick Zombie Survival Guide. Note that Brooks, with his insistence on their viral origin, holds to the biopathological account of zombies -- not the religious/theological account that is briefly mentioned here (under 'Explanation for Reanimation') and such as you find in films like Lucio Fulci's classic 1979 Zombie -- the film that features the legendary underwater duel between -- wait for it -- a zombie and a shark. In the burgeoning field of zombology this is a crucial distinction, not least because means of zombie disposal can diverge quite sharply depending on their type.
When I worked in the pathology lab back in high school, incidentally, we used to get amputated gangrenous legs fresh from the OR that, given their color and texture, looked like they could have fallen off a zombie.
Just thought I'd share.