Ask HN: Most interesting tech you built for just yourself?

A deadman's switch connected to a manner of things. It basically works by 'non-existence' instead of existence and fires a webhook once something stops. For example, if my computer is turned off for a couple of weeks, it will send an email to loved ones. When I go day hiking, something similar happens when my phone loses service/power for more than a couple hours and sends a low-quality gps track. Basically it's if-this-then-that but more like if-this-stops-then-that. I have it tracking all kinds of things, like git-commits-per-person, server/device health metrics, and things like that.

You could imagine a combination of a Tor-like architecture and Shamir's Secret Sharing Scheme to construct a scavenger-hunt encryption system. Maybe 10 dead-man-switch utilities around the world agree to reveal X when Y happens (or doesn't happen), but their policies aren't even revealed until the first N secrets are broadcast. That way you can distribute the risk of collision, and meter the rate of a final secret being revealed or job being executed.