VBS.TV recently did a story on Scopolamine, a substance commonly referred to as "Devils Breath" in Colombia, where it is a common street drug.
This stuff is as close to pure evil as it gets, a tiny amount of the powder administered to the victim causes one of two effects, a) death, or b) complete loss of free will. Criminals are usually hoping for the latter, as it enables them to tell victims to empty their bank accounts, give away their car, perform sex acts, basically whatever the criminal dictates.
This is where Scopolamine has got its reputation as the "zombie drug", victims appear completely sober and rational, but they're really just automatons.
Video Link to VBS.tv story, which documents contributor Ryan Duffy's scopolamine investigation in 9 parts (Flash 9 required). Here's a CNN followup piece.
I'm more familiar with scopolamine as an anti-motion sickness remedy. It's half of a legal drug cocktail known as "ScopeDex" (Scopolamine + Dexedrine), sometimes taken by astronauts and those in training to prevent nausea and vomiting in altered gravity environments. For instance, on "vomit comet" flights. When I flew on an inaugural Zero-G flight for press and celebs a few years ago, ScopeDex was recommended as one way to avoid puking during the flight. I didn't do it, because anything that comes from jimson weed (and other datura relatives) has gotta be evil. But others who've done zero gravity flights (with NASA and otherwise) teased me for passing it up, and joked that scopedex was like a "legal speedball," and not to be missed.
Scopolamine recently popped up in the news as a treatment for bipolar disorder and depression: Link. The drug also has history as a sort of truth serum administered in interrogation environments -- it was used by the CIA in the 1960s, during the MKULTRA program. Woohoo, good times!