This one was interesting.
Since I'm re-watching the entire first Yu-Gi-Oh series (even in light of everything around for crowds both young and old, it still remains as one of my favourite animes), I had a dream last night where I had basically taken on the role of Kaiba, and I was inventing a method of projecting the cards' monsters onto a 3D playing field. It worked as such:
I would print the cards, and each one had a specific magnetic signature left on them (like the actual playing cards, but for my own use). When a card is inserted into the duel-disc, because it's wirelessly connected to a comp, it would interpret the signature and spawn the corresponding monster/spell/trap card in the 3D game engine. How the images would actually be projected was currently under deliberation, as true holographic projectors obviously don't exist. I was thinking that they could be projected directly from the front of the duel-disc onto the floor below as a top-down view, but that would get really messy, as if we want to be able to show one monster attacking another, it would have to all exist on just one projection. Another idea that occurred to me was a large quadrupod stand that you set up over top of the chosen dueling spot, and while that would work much better and would be free from the movement of someone's arm on a duel-disc, it's a peripheral, and therefore would be something you'd have to carry around; I fear that would be a necessity though.
That's probably one of the most logical and productive dreams I've had, and I may actually try doing it, because everything dreamt made perfect sense. It seems like a fun little engineering project.
I have my old Debit card sitting around, perhaps I can play with the NFC-tapping thing; I recall a Mythbusters episode where they were doing that.