Hi, I have read the forums that mention that the Mac Mini's power port on the back has many more pins than are required to supply just power, suggesting future add-ons.
The thought immediately came to me: 'home automation'. This uses signals sent through the power wiring in your home, to turn devices on or off, and in some cases more elaborate control like setting lighting levels, etc. This requires that each device you want to control has an in-line unit on it's power cord, which receives the signal sent by the controller and interrupts the power supply, or allows it through. Lighting can be wired to accept mroe signals than just 'on' or 'off', allowing the lighting level to be accepted. You can extend this to powered projection screens, curtains, air conditiioners, etc.
So an in-line 'Home Automation' unit as a future add-on to the Mac Mini doesn't sound so far fetched. Apple would of course offer software to visually control all the elements, with one 'controller' plugged into your Mac Mini, and extra 'receivers' for each appliance you wish to control. There is even a standard for these signals (I think it's called 'X-10' or 'X10'), which I guess Apple would have to follow in order for it to be widely accepted. maybe the package would be called 'iHome' or something.
Well...that's food for thought anyway. Certainly a product I would buy