Also got a strange Commodore cable.  It has what
looks like a double
 ended HP-IB connector one end and a card edge connector on the other. All
 the connectors have 24 contacts. Both ends have a heavy braided ground
 strap. It looks like it's about 2 foot long. Any one know what this is for? 
It is a Commodore PET GPIB (HPIB) cable.  Most PETs didn't have the
standard GPIB connector (the 8032SK being the only exception I can call
to mind) but had a 24 pin edge connector instead.  The pinout is the
same; pin spacing is 0.156 inch.
The "Parallel User Port" (some useful lines from the 6522 VIA plus some
diagnostic type stuff and video out) was a similar connector with
keyways in different places.  The 8032SK used a GPIB type connector for
this as well, which I found very annoying when trying to connect one to
a friend's BBC micro... but I digress.
(BTW can anyone confirm: is 0.156 inch _really_ 0.156 inch or is it 5/32
inch?)
Philip.