I usually bike in warmer weather and am about to prepare my bike (and myself) to get out there when it's sunny, not too windy, icy, or cold

I usually wear tennis shoes to bike but it's just too cold to do that. I just have regular platform petals right now. I have some SPDs but I don't think I'll put them on until the spring (stay away, salt!).

What do you wear on your feet to bike in the winter?