Calling Winter Commuters:

[nuthatch]

I totally second the recommendation of wool covering as much of yourself as possible. It's nature's wonder material.

[recycle613]

I like the Buff as a neck gator that I can pull up to cover chin and mouth as needed. I find breathing through it is real comfortable and it wicks the moisture or something. It's enough down to about 40 for me. Then I want warmer. They are also great to bring along when you aren't sure what you'll need. They do heads & ears or necks & chins and it's easy to wear 2 or 3 at a time if nec.