There is a Free app for iphones and smart phones that allows your family and friends to track where you are when you travel. Add comments too. iNomad social at the Apple App store or iNomad at the Google android store.
I think the two Apps do different things though. The Instamap appears to allow you to look at photos pf places that other people have posted by location. That's great for deciding whether to visit somewhere.
The Inomad App lets you update your current location and comments from your phone so that other people can see where you are on a map. You can also use the map to see who is near where you are.
We are using it so that our family can follow our trip. and as it updates Facebook as well we are hoping the teenagers might take an interest too. (That hasn"t happened yet though.)
I haven't downloaded Instamap yet, so I may be wrong. I'll let you know when i have tried it.