Invest in an Outdoor Research Baffin Balaclava
Code:
REI

I layered up, wore my Balaclava and rode on the coldest day in IOWA history last January. I think it was NEG. 29 degrees and I think the windchill was NEG. 40 something.
What I wore:
*Balaclava
*bike socks
*thick wool socks over the bike socks
*reg (very airy) clipless mtbk shoes (didn't have any covers over them or put plastic inside...although that does work well when you can't use thick wool)
*thermal tights
*thick lined workout wind resistant "swishy" pants
*synthetic long-sleeve (from Steve & Barry's...$6)
*synthetic warm-up pullover
*sweat shirt
*heavy windbreaker pullover
*mid-weight snowmobile gloves (Menards...$8)