Here is a quick 15 minute video from Evan Sharboneau, author of Trick Photography & Special Effects, on Light painting. I always find this topic so interesting and I love that it can be done with simple household items instead of expensive equipment. Personally, I like to add colored films and cardboard cut outs (gobos) to the light for interesting light formations. This technique can be applied to any field of photography if you think creatively, so the next time you are about to shoot take a flash light and see what you can create.
One of the images I created for a client using a light painting technique on the mask that was suspended with fishing wire and on the backdrop.