When you shoot glass plate negatives, one of the last things you'll think of is storage of the plates. I realized I had this problem when I started cleaning the dust off stacks of plates on my desk. Fortunately for us, archival storage of glass plate negatives is something the industry has been dealing with for about a century now.
For my use, I've found the archival glass negative storage boxes and envelopes available from http://www.gaylord.com/Photo%2C-Print-%26-Art/Gaylord-Archival%26%23174%3B-Blue-Grey-Barrier-Board-Glass-Negative-Storage-System/p/HYB02428 to be perfect for my use. The 4" x 5" boxes listed in the link easily store 100 plates, in a container that will fit great on your bookshelf or on top of your case of 35mm slides. :)