The Serpent and the Rainbow
The Serpent and the Rainbow is a book written by ethnobotanist Wade Davis in 1985. The book is responsible for popularizing the idea that Haitian Voodoo priests can use drugs derived from pufferfish venom (tetrodotoxin) to simulate death in victims, causing them to be buried, dug up, and enslaved as brain-damaged zombies.
The victims are then said to be administered a second powder, this one including datura and part of a recently deceased child's brain. The opinions of scientists on this matter range from plausibility to outright crankery. The obvious ethical issues involved with testing the hypothesis have made it something of a moot point.
One strong argument against this hypothesis, however, is the fact that analysis of the powder revealed pufferfish venom in quantities far too small to have an effect. Davis originally proposed that it was the neurotoxin in the venom that gave the powder its effect, meaning that at least that part isn't true.
On a related note, The TV show MythBusters tested whether someone could survive being buried alive for two hours before being rescued. Host Jamie Hyneman attempted the feat, but when his steel coffin began to bend under the weight of the earth used to cover it, the experiment was aborted. Most of the places where voodoo was historically practiced, like New Orleans, are close to sea level, so these burials are most likely above ground. 
Davis was assisted by Max Beauvoir, who has been elected the head of unified Haitian Voodoo: a controversial move as there is often little hierarchy among houngan priests and priestesses. Beauvoir is the son of a doctor and dislikes the unscientific portrayal of zombies as seen in most Hollywood films. 
It was very loosely adapted into a 1988 movie starring Bill Pullman and directed by Wes Craven.
- The Serpent and the Rainbow by Wade Davis: ISBN 0684839296
- fish in the family Tetraodontidae
- MythBusters.Season 1: Episode 5,"Hammer Bridge Drop, Buried Alive, Cola", Original airdate: October 24, 2003.
- imdb on the film