Researchers in Brazil are looking closely at the Brazilian wandering spider. Its bites are extremely painful and can cause priapism, which is basically a painful erection that could last for hours. (I'm wondering who the poor research subject was who led them to this conclusion!) The researchers purified the toxin, tested it in rats and mice, and found that it causes a chemical reaction that helps blood flow in penile tissue.
Since erectile dysfunction is the result of an inadequate supply of blood flow in the penis, the venom is a promising treatment for the condition. See, people? Although many of you are afraid of them, spiders can be your friends!