I was a passenger on a JetBlue flight in the winter of 2000/1, where air traffic was being diverted from JFK due to a snowstorm, but for whatever reason (fuel?) we had to land there anyway. The runway was basically unplowed at that point. As soon as we touched down there was a sensation we were heading into a skid. I wouldn't really call it a braking skid... it the plane just started turning away from its angle of motion. The pilot somehow managed to slow down before we went off the side of the runway. Ended up stuck in deep snow, partially in a ditch. After what seemed to be some attempts at getting us out if the snow, we were evacuated off the slide. A couple people movers were brought out which we got into, amd which themselves became stuck in the snow on the runway for an hour ... fun times.