Bond Arms makes an over and under derringer model.
Personally, I have no desire to own a gun that is purpose-built to shoot shot-shells, but still has a rifled barrel. Shooting shot pellets through a rifled barrel yields very poor patterning, with a big empty area in the middle of it. But I guess that if I was too afraid of snakes to just swat them with a stick, I might buy the derringer. Although, upon reflection, my home-made .38 special shot loads kill snakes about as dead as they can get.