There are two main strategies for protection from low temperatures; one is
cryoprotectants, the other is
ice binding proteins. The frog mentioned by
no comply uses a sugar (
glucose) as its cryoprotectant, as do many insects. The '
arctic willow gall insect' (which uses
glycerol, not glucose) can withstand temperatures down to -66 degrees centigrade. Chilly.
However, the frog's story is a little more complicated. You may be thinking "if the frog has cryoprotectants, why does it freeze" (you may be thinking something else entirely - if so, piss off!)). The strategy this creature has adopted is to actually promote freezing in the extracellular space (outside the cells) but supress ice formation inside the cell. So it produces proteins that make crystals in the blood while raising glucose levels to 200 times normal. The small ice-crystals that form are less damaging than larger ones (as no comply mentioned they are also 'rounded' crystals) and the cells are protected from the inside by syrup.
The question of whether a) this could be extended to humans and b) this could work indefinitely is tricky. Certainly metabolism in such frogs (and other freeze-tolerant organisms) slows but does it stop? Is there some slow decay in this state - and can all cell types survive equally?
Solution? Participate in your own manipulation!
All information in this node was messily ripped from the heart of : H2O A Biography Of Water by Philip Ball (ISBN 0 75381 092 1) published by Pheonix. Which I highly recommend (read it - if you know what's good for you...).