Recently scientists went hunting for deadly funnel-web spiders. They captured three, brought them back to the lab, and found something curious in their venom that may have some surprising medical benefits for humans.
Venom is bad. It's evolutionarily designed to kill, but, venom is also good. It's a toxic cocktail of proteins and peptides that precisely target molecules in their victims. Once venom hits the bloodstream it works quickly to either thin the blood, block messages between nerves and muscles, and/or some other awful outcome that just does not end well for the prey.
However, if you think of venom more objectively, there are a number of peptides and enzymes in venom itself that can be scientifically extracted and used for good! Scientists are hoping to isolate peptides in animal toxins, synthesize and modify them to treat diseases with no lethal side effects, basically transforming venom from a weapon into medicine.
Seeker: Heroin-like Venom From This Fanged Fish Could Bring New Painkillers
World Journal of Biological Chemistry: Animal venom studies: Current benefits and future developments
Washington Post: Zoo to Australians: Please help us catch deadly funnel-web spiders