I’ll start …
An AS400 back in the early 2000s , used as a legacy system for a leasing company. Some old dude used to come to support it for reporting and other functions. IIRC, there was a nice orange monochrome terminal that was connected to it.
I rarely had to touch it and I left the company before they migrated to a new platform.
I’m sure I’ve ran into more old tech, not sure why this stuck out in my memories.
In the late 90’s we had an old IBM XT tucked away in a corner of the computer room without a keyboard or monitor. It was serving as a “KarlBridge”, which converted from TCP/IP to SNA. It allowed us to communicate with the parent company’s AS400.
The software was on a floppy disk.