By far the smallest micro-livestock opportunity blogged about yet (meant to blog about it last May, anyway). A fellow named Jasper Lawrence heard that being infected with hookworm could be a cure for asthma or allergies, from which he suffered. So he went to Africa and got himself infected by tiptoeing through the feces barefoot. And his sinuses cleared up.
Now he's trying to sell hookworm to others similarly plagued by allergies. In the sequel, of course, the FDA has decided that it doesn't ... um, think he filed the right paperwork. Yeah, that's it. So he's fled to the tropics to spread the love.