Samsung has partnered with Korea university to develop this machine-gun equipped robotic sentry. I so love tech directly from Aliens.
This puppy has twin cam pattern recognition and a 5.5mm machine-gun. The robot audibly warns intrudes before applying the perfect headshot. This little sweetie goes on sale in 2007, for $200,000, and will be "deployed on the border between North and South Korea".
I might get one for the ally way at the back of the house.