MetroPCS Car Dongle

Free dongle, $10 a month for 2 GB! Very nice!

For data users in covered areas this may be very handy.
(Some folks object to being actively tracked - as shown in the comments...)

We don't live in a covered area, but if we did it would be handy for my partner who gets lost rather easily & maybe even worth the monthly cost for help with that problem.

What I find interesting about these OBD2 plugged devices is the location of the car's OBD2 jack;
In Subarus the jack is right where the driver's knee will unplug anything stuck into it during ingress or egress.
To keep such a device plugged in & to avoid endlessly having to insert & remove it would mean dismounting & relocating the OBD2 jack, which might be problematic as state inspection now requires its usage.
(Other cars that I've seen also have their jacks in such physically imposing locations...)