In Live and Let Die James Bond is tracked down at fired upon by self tracking guns, the moment he steps onto baddie Dr. Kanaga's secret compound. Now that nightmare scenario can be recreated at home, using an AirSoft or paintball gun, a bunch of off the shelf parts, and some free open-source code.
The sentry gun picks up its target using a webcam attached to its tripod, which a laptop translates into movements for the servo motor controlled gun. Once the target is in range, it's blammo from gun pelting you with paintballs or AirSoft pellets.
While paintballs and AirSoft pellets can be just fun and games, I'm a bit worried about the potential for hooking this up to something more lethal. How long before we start hearing stories about UPS drivers and Jehovah's Witnesses getting blasted as they walk innocently up to someone's door?