We've seen a lot of DIY home automation projects over the years, but Instructables user electronichamsters shows off one of the most complete systems we've seen yet. With it, you'll be able to monitor just about everything in your house.
Touch Screen Coffee Table DIY With 32" TV and Low Cost CCD Sensor
Adafruit’s Secret Knock Activated Drawer Lock is designed to conceal traditional lock mechanisms – unlocking only when a secret pattern of knocks is detected. Essentially, a solenoid locks secures the drawer while a piezo buzzer “listens” for knocks.