This plugin will simulate a "molten material" effect for the given shape. To make this plugin work, draw some random blobs onto the canvas and start the "Molten Material" plugin from within Filters->Artistic.
These links will show you further examples of the Molten Material plugin:
This script makes a compass wheel that shows the eight main directions. The wheel can be anywhere from 301x301 to 3001x3001. The outer ring can be from 1-15 pixels thick. The pen that makes the compass lines is three pixels wide. The width of the arrows can also be controlled by the "Inner Arrow Thickness" command.
There are no text markings included for the compass wheel, so you can use any font or symbols you want to.
This plug-in will create guides every X pixels apart for the entire image size. It can handle both vertical and horizontal guides.
I wrote this for easier management of multiple textures and sprites in a single image file for graphical programming.
Copy the file in to your Gimp scripts directory, usually '~/.gimp-2.x/scripts'. Refresh the scripts from Gimp menu 'Filters'->'Script-Fu'->'Refresh Scripts'. This is unnecessary if Gimp is being re-started. Once this is done the script can be accessed from 'Image'->'Guides'->'New Guides Every X Pixels'.
Creates a separate thumbnail of the selected image file(s), pre-pends 'th_' (color image) and 'thgs_' (grayscale image) to the filename. WebThumb takes maxPixels as the maximum size of the largest aspect of the image, and then sizes the opposite aspect to maintain the original ratio.
FX-Foundry project is constantly updating custom scripts for each major Gimp release.
Last pack contain more then 100 scripts updated for gimp 2.6
In case you do not need such huge pack you may also search (for category, name, author's name etc) and download single scripts.
Note that many scripts included are not listed in this registry, before ask in this or other gimp forum help to update some old script you may better check on FX-Foundry ,good chances was already updated