This script adds a filter for highlighting the contents of a selection by adding blur and desaturation (both optional) to the layer’s other contents (it creates a new layer for that).
A simple script that desaturates the image the way different black and white films would. The script is based on information from http://www.prime-junta.net/pont/How_to/100_Curves_and_Films/_Curves_and_....
Updated: ver 1.1 - replaced "Flatten Image" option with the more logical "Work on Copy".
there is an update for LabCurves to have a curve for adaptive (or absolute) saturation adjustments. It is an external 16 bit program which can be semmlessly used from gimp with a python script.
More information here: http://www.mm-log.com/blog/2010-07-09/adaptive-saturation-curve-labcurves