I keep an image of anything physical for archiving.
I photograph bits and pieces like cables and disks that belong together, put them in a box and label it according to my electronic file naming convention.
I did the same with all my books. I grabbed the book covers from Amazon.com, made a list of them in a folder called Attic Books, and put them all in the attic.
I also have a shelf of standard-size brown envelopes that contain small things like sets of keys, similarly photographed and labelled.
The image file goes into my electronic reference, grouped according to location, like a warehouse locator [ ATTIC-BOOKS, ATTIC-ELECTRONICS, STUDY-CDs ].
When I need something from my archives, I can search for the description, or browse the photographs by location.