Dedicated single purpose machines. It's nice to have a device that doesn't include all of the usual distractions. For example, I have an old iPhone that only has the PBS Kids app and some pre-approved shows downloaded. Everything else has been removed, so I feel a little bit better about hanging it to a child on road trips and the like. Another old laptop has been covered into a Step Mania machine.

I think old motherboards make nice wall decorations. Just hang them like a picture. Even non-technical people are fascinated by raw silicone. And people get a kick out of removing/installing RAM sticks and CPUs.

Linux Mint XFCE and give them to people in need.

The Android phone might be the most useful, load it up with music or movies and use it as a portable media player or for powering an home stereo (assuming SD card slot and headphone jack based on the age). With the camera you could use it as an IP camera for a security camera. Also depending on the processing power, connecting a Bluetooth controller if you have a PlayStation or Xbox controller that supports it, and loading up some SNES and Gameboy games. I know PS3/4 and some Xbox One controllers support Bluetooth, not sure about newer.

If your home server is enough for your needs, then you can use old laptops for thin clients (tv box, audio streaming client, arcade emulation pc, that kind of thing).

You can also divide and conquer the work of your home server, a download and file manager client, a steam-cache server, a cheap backup nas, CCTV server, home-automation stuff.

This is just a few ideas from the top of my head, but the best use I got from old working laptops were to modernize them (new battery, ssd, Linux) and gift them to people who needed them (students, elderly, etc)

It's tough, because we're about to enter an era where having old, still working tech might actually be a functional boon for a lot of people as the costs of new fabrication explode and the cost of a personal computer becomes nigh inaccessible.

I do think there's a limit, however. I have several older devices that while they have 64 bit CPUs, they have 32-bit bootloaders. Thankfully, Ventoy seems to work well with them still in terms of being able to boot and function properly. But I do wonder if, considering the used market we may soon be sitting in, if all the effort to drop 32-bit support from modern Linux distributions could end up making that market more difficult when there's still some decent-ish devices from that era to do some minor tasks, even if they produce a higher power draw.

To me, the overall power draw is a bigger deal than how old the processor is. If it's an old processor but has a streamlined design that isn't a power hog, then it's still worthwhile. If it sucks up a lot of energy just to do some basic stuff, then it's probably more costly than it is worth in terms of energy consumption. If you can't find any more modern solutions, sure, use the power hog, but I do think the real future of computing is in low-power, high-latency devices as we head into a more fractured future.

Anyway, as for practical use, I don't have a beefy server to run a lot of major services on or to have multiple virtual machines all running at once. I just use actual old machines for headless servers for small services that can fit on and not be overwhelming to these devices. I have a whole stack of self-hosted services on what amounts to (mostly) a bunch of second-hand equipment. Six server boxes, around 25-ish services with about 20-ish of them docker containers.

If you already have one home server, you need two more to make a redundant cluster.

And then you need another set of three to live at a family member or friend's house to receive your off-site backups.

When I still had a static IP I used my oldest laptop as a home server. While its battery life was abysmal and it needed to be plugged in, it was a sort of poor man's surge protection, and also a micro blackout (which we have several times a year usually during storms) protection.

I stuck a 1TB hard drive in it, but RAM and CPU were as good as you'd expect from a 2008 model.

I think people vastly overestimate the resources needed to serve a website, even when it serves media.

Retrogaming machines. Emulators for consoles before the 3D era can run on pretty much a dead hedgehog; you can have hundreds of great games to choose from even on an old system. NES, Super Nintendo, and Genesis are great places to start.

Donate?

Plenty of homeless folks don't have access to tech. There are families escaping abusive partners who could use them.

I used an old phone as an IP camera for years. Worked great until it literally died.

Got a home server running on a Macbook from the Obama administration.

My home is very home assistanty, but I haven't found a good doorbell chime. There are plenty of buttons that work as buzzer.

I've got one of them buttons by the front door. Sends regular notifications to me and the Mrs, and there's one old Android phone in the kitchen whose only job is going ding-dong loudly.

If the devices don't have any broken parts, you could keep at least one of them around as a backup for when your main PC has issues. 2008 laptops are still perfectly fine for e.g. Linux + Libreoffice, and you could load them with a bunch of offline stuff like dictionaries, a text-only wikipedia backup, CD/DVD-based enzyclopedia etc. - this could be quite valuable if your home net becomes infested by malware. I also kept using my old laptop for a long time specifically for its optical drive, because every once in a while I buy second-hand music CDs.

Though in my case, the issue is that my old devices all had hardware issues. My ~2008 laptop has a completely broken keyboard, and a netbook from the same era doesn't even turn on anymore. Most of my old phones have broken screens etc., and the really old ones are unusably slow (maybe I could remedy that by installing a really old android version). TBF, my current laptop is from 2015 and it doesn't look like it's going to stop working anytime soon.

I generally don't think that old PCs are that useful. I don't usually make much use of mine. That said:

• If you don't have a server and need one that doesn't require latest-and-greatest hardware to do something, I think that that's probably a good choice. You already know the hardware. All kinds of things that one might do, fileserving, home automation, whatever. I'll also mention some less-obvious options below.

• Reserve PC. If you have the space to store it and only have one PC, having a second for if something goes horribly wrong on the first can be helpful. Not so bad these days, since most people have a smartphone, and it's not so hard to find a computer.

• Alternate OS machine. If you want to maybe use another OS on bare metal, another machine can be a way to do that.

• Print server/3D print server/pen plotter server. A lot of newer printers have their own print server built in, but not all do. I was looking at pen plotters from Bantam Tools the other day. They don't. Especially with 3D printing and pen plotting, elaborate tasks may take some hours. You don't want to have to reboot your attached computer, and you might want to put noisy hardware in another room from your main PC.

• Security camera server. Detect motion, log images, maybe notify you. Don't want to have the load on your main PC.

• Whole-house music PC. Maybe run something like mpd, which has good support for remote control Hook it up to your fancy sound system.

• Guest PC. Most people do have a smartphone or laptop these days, but it might be useful to have one available.

• Router. I'd probably get dedicated hardware for this and run OpenWRT, but you can use a PC for it, if you equip it with suitable hardware.

I played this game where the people in this apartment building would cobble together video call systems they would use as peep-holes and doorbells with two-way communication. Looked like they were built with old phones, TVs, and other devices they could get their hands on.

I've always wanted to build one. I'll see if I can find the game again.

EDIT: The game was Observer. This is the best screenshot of a couple of them I could find in a couple minutes: