After seeing Seth Godin's post pointing out a restaurant's tea menu in their window which had over 50% of the items messily corrected or blanked out, I wondered if you could make an electronic sign that you could update from the restaurant kitchen as items became unavailable or as the specials changed from day to day. Why stop with the sign in the window, though? You could have the system update a page on the restaurant's web site at the same time... even with an RSS/Atom feed!

The display could be as simple as a flat screen panel with a wireless receiver to avoid running wires... although you would have to design it so that it couldn't be hacked. If you're broadcasting to the sign anyway, chances are that the signal will spill outside of the restaurant. You could give regular patrons a program for their laptops that would allow them to "read" the sign on their laptops as they drive by. That way... they could see the specials without even getting out of the car.

And... why stop at the menu? Why not display what reservation slots are available or how many of the desert specials are still available that night. There's a lot of items and data that could be worked into the system.