There is a newish location sharing feature in Google Maps. I am going to Cardiff this weekend, so I have configured it to run until about noon on Sunday. I tried to enable all my siblings for it, but only John and Vince seem to have Google accounts that let me do so without extra jiggery pokery. It might be handy for them to get an idea of what time I'll arrive, or where I am when I pop out on errands for ma and pa.
I set it up for Paul as well so I could look over his shoulder what this sharing actually means in practice. To my astonishment he was able to work out from it (while sitting in his office) that I had stopped at an ATM when I popped home at lunchtime.
This could take emotionally abusive relationships to a whole new level. Imagine what Jake LaMotta could have done with such a tool in Raging Bull.