I've always had a funny lower-tech idea along the same lines. It's an airplane themed restaurant where each table has one of the service buttons that airplanes have. When you want a server to come by, hit the button. It lights up at the table and at the server station.
The Yo! Sushi chain in the UK does this. When you press the button, something on your table lights up and a cute (usually)Japanese-ish soundbite rings around the restaurant.
