Dr. Julian Tudor Hart's Rapid Response in the BMJ on why treating mildly elevated diastolic blood pressure is unnecessary is perhaps the best Rapid Response to any journal article I've ever read.
The Horse Whisperer's author Nicholas Evans writes of his experience with deadly mushrooms in the BMJ and in so doing does a great job of laying to rest the notion that everything that grows in the ground does so for humankind's benefit. Natural doesn't necessarily mean good.
Cambridge's David Nutt asks whether or not alcohol would be legal were it only discovered today?