Anyone use a Arduino for other things around the home?

[Ryland]

The other day I was thinking about my failed attempt at getting people to install water heater timers on their tank style water heaters, yes I know you can get on demand water heaters but in talking to people I know who service them and install them they have told me not to install one, but if I do that they will give me a great deal on one and a great deal on servicing it... all name brand units too, but this thread is not about that, it's about tank style water heaters and timing them so they turn off when there is no demand for hot water.
How I have my tank set up, it turns on to heat water i the morning before anyone is up and it tends to turn off before any of our peek hot water use happens so as we use that hot water we are drawing off that 50 gallon tank and not reheating it, almost a year and a half and so far no one has gotten a cold shower, it turns on in the afternoon and off again before peek use happens.
Now when I try to explain this to people their eyes glaze over, they don't have a clue when they use hot water, they don't want to worry about setting it after a power outage, they just want it to work, so my question is, how hard would it be to set up some kind of micro controller, like an Arduino to monitor your water use and based off that use turn a relay on and off, in an ideal world it would set up a 7 day pattern, but that might even be getting ahead here, mostly I want to know if anyone who has worked with a device like this thinks it can be set up to do this.

[Phantom]

I have not used one myself but there are several projects on instructibles.com that deal with the Arduino try looking there.