A couple of hikers were out on Mount Hood here in Oregon. They got stuck in white-out conditions and wound up having to build a snow cave to spend the night.
The next day, they found a geocache while working their way down the mountain. When one of their cell phones worked again, they were able to tell rescuers about the cache, and using the GPS location & the clues from the cache, rescuers were able to determine the location of the hikers.
It must have been a pretty easy-to-find cache or they were really, really lucky!