In the same vein, but not necessarily for the same purpose, MRE's now come with a hot beverage bag for heating up water for the drink mixes that come in MREs (they now have mocha and vanilla cappacino along with the old coffee and hot chocolate). It's just a heavy duty ziploc bag you fill with water and put inside an MRE heater. It might be something worth keeping in your pocket in cold weather: an MRE heater, hot beverage bag, tea bag/hot cocoa/instant coffee, and an aqua blox or foil pouch or just pre-fill the hot beverage bag with water. Then, if you lost your pack and got a soaking you could set off the MRE heater, brew a hot drink and use the heater as a hand/body warmer. That would knock off the immediate effects of hypothermia and allow you to function enough to properly help yourself, and it seems like it might be easier and quicker then lighting a fire. The actions involved are all pretty simple: tear open the MRE heater, pour in water,and add the hot beverage bag. The heat from the heater alone should give you enough dexterity to add the tea bag/cocoa mix/instant coffee. And drinking the hot beverage should make you functional again. The only down side I really see is the possibility of scalding yourself, but you also run that risk anyway you try to warm yourself up.