To answer this first question, most of my hardware isn't particularly rare or valuable but is of personal interest to me. Most of it came from the places where I studied and worked, and so for example I have several generations of the machine that was
occs.cs.oberlin.edu, the CS department server for Oberlin College. Those are a DECserver 5000, an Alphaserver 1200, and a Sun Fire 280R; unfortunately I don't have the VAX 11/750 or know what became of it. The CS department did have an Omron LUNA 88K, which would be interesting and valuable today, but I have no idea what became of it.
I'm looking forward to the answer from others on this one - what's the most weird/obscure UNIX hardware you ever used?