Instructable user electronichamsters has a very detailed instruction manual on how to create a home automation system that can:

  • Notify you when the mail arrives
  • Track your dog’s poop and bark locations
  • Monitor for people in different parts of the house
  • Check for water leaks
  • Alert you when the dog runs away
  • Not only check when the washer or dryer is finished, but also if someone has been there already
  • Watch the temperature and humidity in different rooms
  • etc. etc.

using a Raspberry Pi, a few Arduino clones, some cheap sensors from eBay, and openHAB as the brains of the operation.

Head over to Instructables instructions and get started with a cheap but very advanced home automation system.