The hottest prom dresses seem to be those that are barely there, with deeply plunging necklines, open backs, side cut-outs, keyhole openings and slits slashed to the thigh. For the more modest style-seeker sheer or transparent fabric layered over skin or nude lining is a popular choice. Dresses with sheer cover-ups offer a wonderful alternative - they hide flaws well while keeping it sexy. Best of all, they keep you warm at night!!!