Just a quick note for Droid users, if you already have a Droid or will get one for Christmas, the "Where's My Droid" app in Marketplace can not only help YOU locate your phone if it's been misplaced, it can help rescue teams find you (with the guidance from your phone) in the backcountry, on the mountain, etc.
Two features help locate your phone; the text feature will turn your phone from silent mode to ringing loud and flashing, and the GPS feature will text or email the lat. and long. coordinates to another phone or email.
Just make sure your spouse or buddy knows the key phrases that you set for the app. We left the defaults to make it easy, but don't share that with prankster friends!
More about how it works, from the developer: http://ow.ly/1rYaSO
Safe skiing out there!