Some years ago the "Optimus Maximus" keyboard, designed by a Russian designer, with OLED displays for keys went around the world - such a fancy newfangled idea!
I think it took a couple of years until you could actually buy one. For ~1500 € - quite the bargain, one might add.
Of course the idea wasn't totally new - what idea is? - something very similar was mentioned on usenet in July 1981 actually: "Interchangable keyboards".