Back in the man.ac.uk of the early 90s, there were no cameras or YOLO models but we still wanted to know when machines (especially the colour ones! LUXURY!) were available.
We just had "`rlogin` to every machine in the lab, run `who`, and collate the output". IIRC there was an early version written by 'flup that I extended with a tidier output (including an X11 window), auto-refreshing, and easier machine selection (eg. you could select rooms by name with regex filtering.)
Good times.