For this tutorial you'll need to have some basic gimp skills, like creating new documents, working with gradients, adding new layers, etc. We will not be going over these basic steps.
In this tutorial you will learn the basics of how to create a nice lightning effect. Once you know the basics, you can easily experiment to create different kinds of lightning.
This tutorial was created using bleeding edge GIMP, Cinelerra, recordmydesktop, and ffmpeg code, from CVS and SVN repositories on the Ubuntu linux distribution (version 6.10)