I've long dreamed of a dishwasher that can detect when you remove the (cleaned) dishes from it, and presents a display saying 'load dishes' or something like that. And after finishing a cycle, says 'unload dishes'. Should be pretty easy to achieve with some load cells in the feet, but haven't seen any like that.

We had this at my old work, except it wasn't a display, it was a circular piece of paper with "clean" on one side and "dirty" on the other. When it was done, you rotate the paper so it was clean side up. Should we have gone for series A? It was a pretty great MVP after all, albeit manual, but automation of the paper flipping would of course come on the second iteration

Many modern ones have a door open sensor that allows for the dishwasher to display that dishes are clean after a cycle until the door is opened and fully closed again.

That doesn't help, however, if users are lazy and don't unload the dishwasher after opening it to grab a clean plate or whatever.

It's a nice feature that can be added with existing sensors and one line of logic in the uC. Another one I noticed recently is garage door openers with the photo transmitter/receiver ('beam') to stop the door if someone blocks it can use that same beam to turn on the light if broken when the door is up. Handy if entering a dark garage from outside.