Well you will not find on the registry, not even on gimpscript or discussed on gimptalk or here
Are a series of
python script i found on the meetthegimp forum
http://forum.meetthegimp.org/index.php/board,12.0.html One of the contributors is rayadagio
http://www.rayadagio.de/manufacture.html with
Colour Negative Inverter :Because of the more or less orange material of analogue colour films it is not very easy to invert digital copies of these films. Manual correction of the orange colour cast may be very difficult. This script performs an automatic colour correction and inversion.
2) Digital Graduated FiltersThis script simulates graduated gray filters (GND) and graduated coloured filters. Two differently exposed images of the same subject can be combined to get a well exposed image with a soft gradient. Some options are included to control intensity and colour of the gradient.
3) Automatic Creation of Selections and Layer Masks - The Range Selection ScriptThe Range Selection Script is a tool for easy and automatic creation of selections and layer masks. The selections or masks include all parts of the image that are situated within a defined range of tonal values, colours, saturation or edges. Selections can be based on one of 16 channels.
4) Another Way of Rotation - The Straighten & Crop Script
The GIMP rotation tool is quite good. But I think straightening an image could be done even a little bit easier. I like the way it is done by my former image processing program more than working with the grid of the GIMP rotation tool. So I tried to imitate it by a script. Now you just have to place two mark points on a line that should be exactly horizontal or vertical after rotation and to run the script.
again all those are on
http://www.rayadagio.de/manufacture.html --------------------------------------------------------------------------
Of same author but for less specialist use Frame Factory , but have a look yourself to the examples
http://rayadagio.de/framefactory.htmlBut are even more from others authors hanging on in the meetthegimp forum
for all plugin listed below the link is
http://rayadagio.de/?page_id=26 (SCROLL DOWN and look at right)
CA correction with Hugin
clipping detector
colour negative inverter
dramatic script
dri tool
easy zone adjustment
fading colourisation
octave sharpening
resizing with ImageMagick
selective brightness
selector
Most were discussed on the Meetthegimp forum too (link on top)