I like making weather stations out of these. Updating once every 30 minutes, you're usually not looking at it when it's refreshing anyway.

Though my next project will use the smaller 1.54 inch ones, very targeted ;)

The last HN article with the Lilygo T-Display (ESP32-based) that showed the news articles was cool, and screwing around with that led to finding an open source weather program for the better T-Display S3. Stupid easy, cheap and fun to throw together or mod.

https://github.com/alexphredorg/lilygo-weather-esphome

you'd think they'd be useful for safety critical logging. You can guarantee some information on power loss like GPS coordinates, error states or situational Info like tidal information.

I always wanted to try overlaying physical controls for realtime readouts but use these displays for generated backgrounds like gauge scales. Or like a clock background that still had physical hands.

I am currently building an auto-updating webcomic display for a community bulletin board. It's of course a great application for an e-ink display because it only requires power to update.

Further implementation details: I'm using an ATTiny85 to feed 120 seconds of power-on time to a Raspberry Pi Zero W every 12 hours or so, via a MOSFET. That way I don't have to keep the RPi powered on. Power source is 3 D-cells.

Picture frame

The first iPhone had a 3.5" display.