Wonder what dunking one in a vat of liquid nitrogen would do.
There are so many factors that go into preserving tissue or embryos at cold temperatures. Bodily damage from hypothermia is due to a number of factors, including the inability to circulate blood to tissue, decreased enzymatic activity, etc. In the case of 0 C or below, you have additional concerns such as the formation of ice crystals, which will lyse cells or exude into the extracellular spaces, concentration of harmful solutes. Flash-freezing results in vitrified (i.e. glass-like) water that won't form ice crystals, but it's very hard to flash-freeze a heterogeneous object like a living organism all at once.
Based on what I've read, a werewolf could probably survive third degree hypothermia or even being frozen, but it'd take a while to recover as ALL tissue would be damaged to various degrees and there'd be irrevocable damage to the CNS (central nervous system), which is one of the few things lycanthropic regeneration can't restore perfectly.
What about powerful acids? There really aren't any acids on the level of, say, xenomorph blood - the ones that come close are too unstable (
http://en.wikipedia.org/wiki/Fluoroantimonic_acid). High molar sulfuric acid will sting like hell and leave very nasty scars, but it's not going to melt you in a matter of minutes like you see in the movies; even overnight suspension - while definitely killing the poor victim - won't completely dissolve a body and will leave teeth behind. Then again, it destroys cells and tissues on a molecular level and is in some ways just as bad (or worse) than fire.