This plugin is creating a number frames around a selection with increasing opacity. Rectangle, ellipse and diamond possible. Example see http://www.gimp-atelier.org/forum/viewtopic.php?f=69&t=358
You will find this script on GIMP at Filters / Gimp-Atelier/Darken Frames ++ or if you are working with menu with reduced size (height 755 pixel) at Filters / Gimp-Atelier/Darken Frames
English version: darkenframes_en.zip
Reduced Menu: darkenframeswin_en.zip
Unless otherwise noted, the rights for the individual plugins are with their respective authors. Logo image by Jakub Steiner.