Web site Light Doodles teaches you how to draw in a photograph using light. What the heck's a light doodle? See an example in the included image, and hit the site for a video of how that was drawn.
Light doodling or light drawing can be described as the simple act of capturing the trace of a narrow moving source of light using long exposure photography, long being defined as seconds or minutes. The moving light source will then appear in the finished picture as more then what actually exists and is truely a representation of time as well as space and movement.
This tutorial covers what equipment you need, your camera's settings, good light sources, and advice on what to draw and how to draw it. If you give it a try, show off your light drawings in the comments.