The North American wood frog is quite a peculiar animal. Unlike most frogs, the wood frog can be found in Alaska and above the Arctic Circle. As the temperature drops below freezing and as soon as it "just touches an ice crystal", the frog will completely freeze. The frog's organs stop functioning -- no breathing, no heart beat, nothing -- for several weeks. When Spring arrives, the frog then spontaneously thaws and, within hours, is ready for mating season.
Sound like something in a sci-fi movie? See for yourself. Link.