What's the rarest or most unusual computer-related item do you own?

[Jon Elson]

OK, I have some TINY core planes out of a Honeywell system.  
One unit was a tape drive, the other a line printer.  These 
were hooked together to make an off-line print despooler.  I 
got it working enough to analyze the signals, and then wrote 
a driver and built an interface to my S-100 Z-80 system.  
So, I had a 300 LPM drum printer on an S-100 system.

All I have left of it is the core plane cards and a few 
other bits.

I also have a PDP-8 core plane.

Jon