I've got quite a few Raspberry Pi boards, including an original one that I bought at @oggcamp in 2012. I think it's fairly rare because it only has 256MB of RAM. Anyway, I decided to see if it can actually do something useful so installed Pi-hole on it.
Although it's quite slow when I have to ssh in and deal with config, the web interface is pretty responsive. I've been using it on my phone for a few hours but it's absolutely fine.
So maybe the Pi 1 is actually useful!