A best bet is the Mammoth EVO Unisex Clog Faux Fur-Lined Clogs in seven colors (Graphite/Oatmeal pictured) for $44.99 before the above coupon, $26.99 after. With free shipping, that's the lowest total price we could find by $15. They're available in men's sizes 4 to 13 and women's sizes 6 to 12, although not in all size/color combinations.
Meanwhile, Crocs also takes an extra 25% off a selection of Crocs men's and women's work and RX shoes via coupon code "YAYF2012". The same shipping rates apply.
Orders aren't guaranteed to arrive by Christmas.