It looks like adding ski areas is labor intensive, so perhaps you could publish the method for mapping a ski area, so users could map their local areas and submit them for incorporation into the website.
Another feature that would be cool, but perhaps difficult, would be to have the google earth plug in support fly thoughs down trails, with the perspective a skier would have as they remained perpendicular to the slope. This would give a nice preview of various trails for people considering trying a particular trail.
It might also be nice to get trail statistics by highlighting a particular trail, such as total vertical drop of the trail, total horizontal distance of the trail, and surface length of the trail taking slope into account.
A way to toggle an overlay of the ski resort’s trail ratings off an on would be useful, so people could compare the ski resort’s trail ratings with the actual slope. This would give an idea of the resort’s philosophy for rating trails and you’d know what it means when they label a trail a blue for example.