GIMP Plugin Registry

This Python plugin simply can lay out all layers of an image into a grid (with the grid settings changed to reflect the old image size). And it also does the inverse, creating one layer for each grid cell in the image. This can be useful for things like a sprite sheet or glyph sheet and I didn't find anything similar.

Gino D's GIMP Scripts:
https://sites.google.com/site/ginodonig/gimp-scripts
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This script creates an image filled with a texture representing a crossword grid with a random placement of shaded cells. It is equipped with several options which permit to define the main characteristics of the pattern, to the point that it is even possible to obtain styles and variants of crosswords that break with tradition, namely the grid will be allowed to be colorful, not symmetrical, oblong, and so forth.  read more »

This script will construct either a hexagonal or triangular grid. It's a kind-of follow-up script to the circular grid one I made a bit earlier. (If you wanted that one instead, look here: http://registry.gimp.org/node/25206)

You choose the size of the image, and the length of side of the shape. The shapes can be filled with up to six different colors, a white background, transparent, or completely random colors. There is also an option to set up the grid so that it will tile seamlessly. I've attached a picture showing a hexagonal tiling grid generated with this script.  read more »

This script sets guides at every 10% Vertical and Horizontal.