I don't know if software counts as gear, but hoping this is the right place to ask… Is there an app which can send updates of your location back home, sort of like spot messenger? Of course, a data connection is required for this, so it would be only useful in areas where there's mobile signal. Nevertheless, in some areas this does happen semi-frequently, e.g. on top of summits, and I think it would be nice for multiday trips to have a way to send a few pings back home in this way. Ideally, the app would store your progress/coordinates on a server, and people could track your progress from there (where you last were, at what time, etc). Alternatively, more simply, it could send an sms with your coordinates, or a time-stamped link to current position in google maps. (Of course, if you have signal, you could just call home, but that's not the point!)
