I found these last night in my local outdoor shop. They are high-tech fleece pants designed to be worn under fishing waders but they work perfectly under my snowboard pants. They have an articulated cut and are nice and baggy to allow free movement. The best part....they have elastic stirrups that loop under your feet so they don't work their way out of your boot througout the day! Also, zippered pocket for really hiding and securing your valuables.
Columbia Sportswear | Men's Columbia Wader Pant