Sentry Gun
This page is a stub; I'll write more later.
For now, you might like to know that this project depends on my PWM modulator to control two servo motors, and will use a web cam and FOSS facial recognition software from USCD. Since I don't particularly want to debug a circuit which can fire a gun, it will use a laser pointer until the bugs are gone. The laser gun and arm were tested with my laser light show clock.
It is inspired by this project. Similarly, a reader Gabriel Holmes pointed out this similar project.