any of the pac boots known as "maine" boots are warm to xtreme, similar to the Mickey Mouse boots referred to above. There are also heavy duty mittens with liners and outer covers meant for arctic conditions.
Though maybe not the best choice for winter but non-snow hiking, I like Steger mukluks. I wear them snowshoeing and light hiking. I wore them on a winter vacation to Iceland, to watch the northern lights at midnight in howling sub-zero wind. The muks are impermeable to cold (my opinion), but great is they breath wonderfully; your feet will not sweat in them over a fairly wide range of temps. They are pricy though.
The inserts of all the above are made of wool. I would recommend staying with wool over any synthetic for best results in your case.