GIMP2.8 Script-Fu is a collection of over 100-scripts free and available for download. Vrious pencil strokes, contrast, edges, effects (bevel selection, etc) shapes, etc are available in Script-Fu.
here is how to get Script-Fu installed on a Debian box.
1) download the Script-Fu bundle from here: http://www.gimphelp.org/script28.html#downloads
2) Launch GIMP,Continue Reading: