In this photo I was playing with my flash settings and second-curtain sync (aka. rear-curtain sync) on my Canon 30D. What this does is fires the flash at the end of the exposure and not at the beginning. This gives the effect that the subject is moving forward. And by placing a tissue in front of the flash unit I made the light source larger and lessened its power thereby giving the subjects a ghostly not solid appearance.
Camera specs: Canon EOS 30D with Canons EF S18 – 55mm lens, 1.3seconds at f/8 @ 18mm, ISO 100, Aperture priority