Oh, that sounds like fun!
I have often thought about what I would do if I ever buy my own house...
My house would have to have an "engine room", somewhere where all the electrics, server, network,
telephone stuff could be installed.
1. central light control. All lights have to be switchable from a central control, thus enabling automated
switching of lights while away to deter burglars.
All lights could be switched off together by a single switch when leaving the house.
2. central power shut-off. Same as lights with all other appliances. You would never have to worry about
stand-by appliances. Everything's off when you leave the house. Could be controlled by the door lock,
when door gets locked the house assumes that nobody's in it and switches itself off.
Refrigeration and heating devices would have to be excluded, of course

.
3. automated garden watering. Either timer controlled or by sensing humidity of the soil.
Could include a pump and rain water cistern to save water and money.
4. burglar alarm. Either with reed contacts on doors and windows or IR sensors in the rooms.
Can also be tied into a central server/communications system that calls your mobile and/or police.
Now it gets really ambitious:
- electric sheep: A robot device that mows the lawn
- electric house maid: A robot device that vacuums the house while I'm out. I'm thinking about a
real vacuum on wheels here, not those rubbish little Roomba thingies.
One problem you have to think about: If you ever have to sell your house this stuff could potentialy
be troublesome. I wouldn't buy a house where some madman has installed a self designed home automation
system...