Ask HN: What do you do with your Raspberry Pi?

Use it as a SPI programmer with flashrom, to flash bios mostly.

I run pihole for my whole home network

I use my Raspberry Pi's for a variety of purposes. I have individual Pi's operating as a home router, retro gaming system, home automation hub, and 3D printer management system. I have a cluster of Pi's which runs several applications including a Plex server, Ubiquit UniFi server, BitTorrent rig, Nextcloud server and some other miscellaneous projects of mine.

I use mine to run WeeWX (weather station). It has an RTL-SDR attracted, receiving from an Acurite 5n1 weather station. The official Acurite bridge was obsoleted/disabled a while back, so this is what I did rather than buy the "new and improved" bridge.

I have a Pi Zero W with an external SSD hooked up to my TV for playing back video files using Raspicast for Android.

I use a Pi 4B as a dedicated web server and UPS controller.