I have one pretending to be a grandfather clock (it used drive a servo that rang a physical chime via a little motor driver controlled by GPIO, but the servos would burn out every year or so, now instead cron just plays some .ogg files of a clock striking). But for straight-up servers, wouldn't a bunch of docker containers (or even some shell scripts and cron) cover many of those other uses? I tend to think of the Pi as a sort of 'physical container' that gets me a full OS (with networking, package mgmt etc.) which can be great if you only need one thing in one place, but I also have a little fanless NUC-alike running a bunch of containers.