The home as a user interface
Recently I've spent a lot of time thinking about the future of home automation. There's a lot of chatter about the internet of things, most of which relates to having lots of sensors reporting data back to servers so you can see what's happening at home. That's all very well, but personally I think that sensors in the home can also act like a gigantic input device. In effect the sensors you have in your home become a giant keyboard, and as you 'type' by simply moving around, opening doors and such like you are providing input to a home automation system that will then act and respond. The interface of the future isn't fancy touch-screen keypads in every room, it's an invisible network of sensors that know you walked upstairs, opened a door, are standing near the fridge etc.
For example, in our house, you don't look at a screen to find out who called while you were out, instead the mere act of coming home, opening the garage door and then moving into the kitchen triggers an announcement over the speakers telling you that you missed a call while you were out. You didn't need to press anything, you didn't need to look at anything, the house simply responds like a human butler would do and speaks to you at an appropriate time. The algorithm is actually rather more complex than I implied as it doesn't blurt it out right away as you stagger through the back door with arm fulls of groceries, instead it waits until you've moved around in the kitchen for a while and then it makes the announcement.
Another example is the link between open doors and air conditioning. If you leave a door open to the outside, after five minutes it will warn you and then after a few more it will turn the A/C off.
Yet another example if the warning it issues in the evening if you left the garage doors open. A simpler system might just repeat an annoying warning over the speakers every half hour after 8PM. My system waits until you are up and moving about before telling you so you get the alert when you are ready to act on it and it never disturbs you while you are sat still watching TV.
The house is the user interface.