A long while ago I was thinking about how all electrical stuff in the home is incredibly dumb, its not its fault it was built that way. The problem with anything in the home is that infrastructure is expensive, especially in old homes (mine is 105 years old, insulation would be a start). One of the reasons that wireless has become so popular, to the extent that people just forget how well cables work. One day I'll be able to get a Gbps over wireless and I'll be happy.
Anyway back to the point, houses are dumb. I was thinking that is should be possible to hijack existing infrastructure. Specifically light switches and sockets, they are all over the place, the conform to a standard size and they have power.
So why now, well I've just seen a video of an Arduino micro controller working with a touch screen. Now I know its possible to communicate over power lines, and you could throw in a load of sensors: temp, infra red, sound etc. To Actually do stuff you would need a speaker and probably a big fat mains switch but that again is totally doable.
So what coud you do with this setup, here are few ideas:
All I need now is for Apple to go out and build them, shiny. Google have made a move in the right direction with the Android Open Accessory stuff, but that will be less shiny.