Cross-country skiing in winter can be a wonderful activity with great views to the snow-capped mountains nearby. The ski lodge is located at Tamarack Lodge, off Lake Mary road a few miles southwest of town.
Ice Skating. I rarely see anyone at the ice skating rink, but its a nice cheap way to spend a few hours with the family.
Most people don't ski sail...actually I'm about the only one. It's me and a group of kite boarders on the Mammoth Meadows.