A "survival wiki." I built it for myself. It's mediawiki on a raspberry pi zero, AC/DC powered, with an e-ink display. It connects automatically to a known wifi network and displays the connection details. When the wifi network goes down however, it automatically switches to access-point mode, allowing you to connect directly to it through your phone or other wifi client device.

There's still some quirks to work out, but it works well. I store personal knowledge on it and I don't have to worry about rebooting my primary computer (and taking down the wiki), or a power outage preventing me from accessing my information.

https://drive.google.com/file/d/1CTYjKq0DLYVV7LBktW-bQrxZv2F...