I debated posting this one, as it's not as rare or old or desirable as some of the really cool stuff in this thread. But it's my stash of NOS/NIB Shimano 7-speed cassettes, to keep those bikes going for a few years.
You can see most of them are at the HG50 quality level, with an IG60 11-28, an HG90 12-21, and a low-miles HG70 13-21 (no box, upper left corner) to round things out. I got the two late-90s HG50 13-21s in the small boxes from Boulder Cycle for a song! Here's what a representative sample of the cassettes look like:
I don't have specific plans for everything in this box, but I'm glad I bought them by the handful when they were about $20 each. Nowadays, 7-speed cassettes with "road" gearing aren't nearly as plentiful or cheap. At least from Shimano.