

I’m hoping for MacroSD. About the size of a 3.5" floppy so you won’t lose it easily.
Seriously, it’s interesting that now that we have the tech to make a useful-capacity storage device the size of a credit card, we don’t. Not like those crappy giveaway flash drives printed with a card design, where they had a captive USB head and were 4x as thick as a card, but something with just contacts like a chip card, so you might need to use an external reader but it really preserves the wallet-size concept.
I’d love to have a cheap 16GB card in my wallet with all my health records and a cryptographically signed copy of my will as a one-stop, no cloud required, emergency kit.
There’s also the Ploopy, which is modern-oriented but a competent DIY trackball.