When my wife and I tour, we use a Spot with the tracker option. My father in-law gets up early to follow our ride (we usually hit the road around 3:00 AM). He's nearly ninety years old and this is fun and entertaining for him. Someday I need to learn to work the ridewithgps stuff so we can upload gps-tagged photos for him to see; he'll like that too. We have a few other friends and relatives who get the data just in case something should happen and so they have some idea of when we will be back if they happen to be tending our animals or plants for us.
The cost is moderate, although far from free, and it gives us some benefit. For others, it may not be worth it. I bought the thing when I was heading out for a short tour and my wife wanted to know where I was in case she needed to pick me up. I was heading down from Eugene to Davis and had a date I needed to arrive by. She was heading the same way but was going to choose between driving and taking the train. If I managed to take too long on logging roads in the hills, which I much prefer to the crowded flat coastal roads, then she would drive and I'd head to an easy-to-find meeting place.