I've been wearing ski goggles at night to avoid the same problem, but I haven't liked how they restrict my view when checking lanes over my shoulder. I found these online for $10 after shipping:
http://www.discountsafetygear.com/crstsago.html.
They are clear safety goggles that have been treated with an anti-fog coating. I should have them in a few days and will post a review on how they work in the cold.