I've seen an very interessting video (http://meetthegimp.org/episode-127-octave-sharpening/) about the so called "Octave Sharpening" I've never heard. So I started searching for some information about it and found also 2 other sharpening methods (http://www.varis.com/StepByStep/sharpen/Sharpen.html).
The PDF tutorial (second link) shows the function with Photoshop so I implemented the scripts for gimp and wondered how effectfull they are.
Here is version 1.0. Any feedback welcome...
Copy the files to your Gimp script user folder:
Windows: C:\Documents and Settings\[USER]\.gimp-2.6\scripts\
The scripts can than be found in Gimp under:
Filters --> Enhanced --> ... Sharpening