The EasyCard (悠遊卡) in Taiwan. It’s an IC card frequently added onto just about every other card, like bank cards, student ID, or you can just buy one at the convenience store. You can store value on it, use it to ride metro, trains, busses, ferries, rent a share bike, buy groceries, anything at convenience stores, pay for food at lots of places, badge into buildings, and I keep learning more things I can do with it. The card, of course, is just a card, but the network and the number of things you can use it for is amazing.