Index cards played a large role in the decipherment of Linear B. "It was Dr. Kober who cataloged every word and every character of Linear B on homemade index cards, cut painstakingly by hand from whatever she could find. (During World War II and afterward, paper was scarce, and she scissored her ersatz cards — 180,000 of them — from old greeting cards, church circulars and checkout slips she discreetly pinched from the Brooklyn College library.)" This is what it looked like:
She recorded on these cards statistics about each character of the script. They were stored in cigarette cartons.
Thanks to Michael Leddy for calling my attention to the story in the New York Times Sunday Review of May 11.