Accidental Discoveries in Medicine

Accidents in medicine: The idea sends chills down your spine as you conjure up thoughts of misdiagnoses, mistakenly prescribed drugs, and wrongly amputated limbs. Yet while accidents in the examining room or on the operating table can be regrettable, even tragic, those that occur in the laboratory can sometimes lead to spectacular advances, life-saving treatments, and Nobel Prizes.

A seemingly insignificant finding by one researcher leads to a breakthrough discovery by another; a physician methodically pursuing the answer to a medical conundrum over many years suddenly has a "Eureka" moment; a scientist who chooses to study a contaminant in his culture rather than tossing it out stumbles upon something entirely new. Here we examine seven of medical history's most fortuitous couplings of great minds and great luck.

http://www.pbs.org/wgbh/nova/cancer/discoveries.html

Here is similar article from the Discovery Channel:

http://www.exn.ca/Stories/2004/04/19/51.asp