I have Shimano M180 MTB shoes, similar to this. They have a quite small heel tread area.

I got some Louis Garneau shoe covers at the LBS. These are cloth, with a fuzzy interior layer, not neoprene.

I usually wear 10 1/2 or 11 shoes, but have 11 1/2 mtb shoes, which work great with thicker wool socks. The shoe covers are Extra Large and fit perfectly. (I've removed the toe spikes). The elastic fits right in the instep, so the front and back tread can be walked on. At the store, I didn't think they would fit at all, but the elastic parts allow it to fit snugly.

I was riding at 33F on Saturday, and my fingers with two layers of gloves were cold, but my feet, with wool socks and the shoe covers were fine. The covers and wool socks aren't too warm even over 50F. I was really surprised how much of a difference they make.

Now I have to go read the gloves thread!