Apart from some performance and usability issues this is one of the better piste visualisations I have seen.
To be truly awesome it could use some context. For example: villages, roads (only those open in winter), restaurants and piste facilities, but most of all: accommodations. I can easily see myself using something like this to compare the location of various chalets, apartments, hotels etc. Partner opportunity?
Also it would be great if you can browse neighbouring ski areas. This is something most traditional maps lack – but I can see it becoming a great way to browse for nice runs in a certain area.
Edit: Oh and it would also help to at least include the actual ski area names. I was looking for "Portes du Soleil", but you have listed it as "Avoriaz", even though you seem to have included the entire area.