It might be too outdated to do major services, but it's still fine for its original use - interfacing with electronic components.

You could build a weather station, monitor temperature and humidity in your attic and crawlspace, automatically water plants, etc. You don't need much electronics knowledge for that sort of thing.

I had a really important role of my Pi 1 B+ for a long time; it was a network storage for my PlayStation 2 to play ISOs from the network with Free McBoot and Open PS2 Loader.

grabbed a big HDD, and old CD drive case and put everything inside. The Pi could be powered from the PS2s USB, hooked up a short network cable and it was ready to go.

Tho I still have that PS2, it's not in use anymore, so neither the Pi.

Mine is my DNS. Pi-hole with unbound.

This would be perfect for a BBS.

Mine is still going strong and runs my irrigation system with the gpio interfacing with a relay board.

The original Pi B had a single core 700mhz ARMv6 processor and 512mb of memory. It's fine for embedded projects using GPIO or a mini LCD screen, but that's about it. You'd be lucky to even decode 720p video on it as a streaming box.

It might work neat as a monitoring device to keep tabs on the rest of your homelab machines and display a status output or something.

ADS-B receiver that uploads to ADSBExchange, Flightaware, and FlightRadar24. Start tracking the skys

I was wishing I had one just recently. I'm not smart enough to get my ancient APC UPS to interface to Debian with the USB cable, so I need a device I can ping that's plugged into the mains (ie not through the UPC) so I can run a script that shuts the server down when the Pi stops responding to the pings.

So that's all it'd need to do - respond to pings when it's powered on. I've ordered a B+ for exactly this job.

I use mine as kitchen radio with https://moodeaudio.org/

I was using it for Pi-hole all the way up until I got a 4b and then put Pi-hole in a docker. Solid dude, will be hanging on my wall like those disassembled iPhones

I was thinking about hooking one up to a GPS module to run a local NTP server

https://blog.networkprofile.org/gps-backed-local-ntp-server/

I don't see why it wouldn't handle SyncThing, as long as you're not syncing a lot of clients.

You could also get a cheap screen and use it for a news/weather/social feed.

Make a Pi-hole for friends/family, unless you want to build discrete hardware projects that don’t need a fast CPU. My 17-year-old niece is doing breadboard projects on this gen of Pi.

i use an old pi1b to run rtl433 with some even older dvb-t stick to grab weather data from my neighbors (who can afford a brand new bresser weather station with wind speeds and everything etc..) and send that to mosquitto for use with home assistant. but can track even more...i figured out car tire air pressure sensors and other stuff give me a good insight on wether the neighbors are home or not.

I know you have an adguard, but have you thought about ditching those and using pinhole+unbound?

I have the exact same model sending me birthday reminders daily. Scraped all my facebook friends’ birthdays years ago and made a very basic telegram bot. Saved me more than one embarrassing moments, including today, as I completely forgot about my brother’s birthday.

I had a pi 1b running my hvac/humidifier/HRV unit at home for years. Only removed it when we moved out.

Related to OP's question: is it possible to have the 1B boot from something other than an SD card?

I ran it as a PiHole for awhile, until it chewed through two SD cards. I'd like to use it for the GPIO functionality but I don't want have it randomly crap out again.

Since its GPU has composite out, why not a cool arcane cabinate?