If head lice really creep you out, don't look at these pictures.
Rick Speare, who was a professor and researcher at James Cook University, developed a great slide show on the biology of the head louse. Check it out here. The pictures are amazing and show an indepth look at the louse's specialized parts. (In this picture, I imagine louse saying, "I'm a survivor!") These pictures and explanations can help you understand how a head louse operates. Very interesting stuff, but it also just goes to show that any bug, when you look at it closely enough, looks sort of like something from "Alien".