Here in the Boston area we have Dr. Murray Hamlet, a researcher formerly at the Army Research Institute in Environmental Medicine. He is someone who knows just about everything there is to know about being out in the cold (and I do not say that lightly). He has given being-out-in-the-cold talks at REI and the Appalachian Mountain Club.

One of his recommendations is to spray your feet with an antiperspirant (not deodorant) for a couple of weeks before going out for an extended time in a high threat cold environment. This will seriously reduce the amount that your feet sweat and keep your socks drier and thus keep your feet warmer.

It is an easy experiment to try; simply spray one foot in this fashion and not the other. See if it makes a difference when out in the cold.

Hamlet also has developed sock systems for all-weather and extreme weather situations. See http://techspun.com/whichsock.html and http://www.techspun.com/comments.html.