This website explains exactly how to matte in your own light-saber effects on your homemade movies, from how to construct an easy-to-rotoscope saber right up to using video-editing software to add the light-beam.
(Thanks, IZ Reloaded!)
I write books. My latest is a YA science fiction novel called Homeland (it's the sequel to Little Brother). More books: Rapture of the Nerds (a novel, with Charlie Stross); With a Little Help (short stories); and The Great Big Beautiful Tomorrow (novella and nonfic). I speak all over the place and I tweet and tumble, too.