I only have two of my three WYSE-150's left, and I kinda miss it. Having a modern dumb terminal could be really cool, as it means I could lay out my 100-foot serial cable from the server to the kitchen, and issue commands to play music while I cook.
Yes, I bought a 100' RS232 cable from BlackBox just so I could do that with a WYSE-150. Never got much past proof-of-concept where the terminal was about ten feet from the server, but still.
I suppose the third add-on, then, would be bluetooth. Have it register as a serial device, and you'd have a wireless dumb terminal with a color screen.
I'd buy it.