Script-Fu

Gimp 2.4

(en) To create web page buttons style Aqua Bou - For The Gimp 2.4.
This version is for Gimp 2.4 or higher (with Tiny Scheme interpreter).
For The Gimp 2.2 or lower version (which uses the SIOD Scheme interpreter), I suggest you use the Aqua bou version 2.2 .
Once installed, restart the Gimp and access the menu: File -> Create -> Web Page Themes -> Aqua Bou -> ...

Gimp 2.4

(en) To create web page buttons style Aqua Pill - For The Gimp 2.4.

(pt-BR) Para criar botões de páginas web estilo Aqua Pill - Para O Gimp 2.4.

To draw all the regular polygons in parametric modality

Script Tutorial: http://xoomer.alice.it/lwcon/gimp/script-fu/draw-polygon.htm

It reduces global contrast in images while increasing local contrast and shadow/highlight detail. Use this to make your images "pop."

This script creates shiny-looking 3D logos, similar to that of a well-known search engine.

The original script lives under Filters → Alpha to Logo → Google Effect. It creates a 3D logo from an existing image. For example, this:

Turns into this:

Creates an outer border of the image with reduced brightness and 2 inner colours.

Uses one colour for the highlights and another for the shadows. The following photo was created using the default colours:

Before:

After:

Script to Draw dashed lines with GIMP in parametric modality.

Script Tutorial: http://xoomer.alice.it/lwcon/gimp/script-fu/draw-line-trat.htm

This Shadow&Highlight script does a decent job of lightening shadows and/or darken highlights in photographs. The UI gives you five control sliders. Two for control of the Shadow and Highlight amount (opacity), two for the tonal width of each contrast mask layer (using gamma), and one for the blur radius of the masks. Plus the option to flatten visible layers when done.

To graph the trigonometric function sin(θ) or cos(θ) on the image

Author web site: http://xoomer.alice.it/lwcon/gimp/

Script Tutorial:
http://xoomer.alice.it/lwcon/gimp/script-fu/draw-function.htm