GPLv3

Takes a wide panoramic image and bends it into a rainbow-shaped image in a way that preserves scale and aspect ratio.

is morphed into

Partitions an image into tiles (with, optionally, either gaps or overlaps between them) and then writes each tile as a separate jpeg file.

An alternative method of doing the same thing would involve first setting up a grid of guides (eg, http://registry.gimp.org/node/12003), then using Image->Transform->Guillotine (as noted here: http://registry.gimp.org/node/20826), and then saving each of the generated images to a file.

Takes an image, makes four 1/4 scale copies, and reflects them about vertical and horizontal axes to achieve a four-fold symmetry.

Note: As well as being atrociously inefficient (eg, by scaling the same image four times, instead of making copies after the first scaling), this code does substantially less than the "Small Tiles" dialog (which comes standard in Gimp in /Filters/Map)

Provides a kind of poor-man's HDR (high dynamic range). It doesn't actually increase the dynamic range; in fact, it decreases it, overall, but in a way that maintains local contrast. But this gives you some headroom to increase the contrast of the image overall, thus enhancing the local contrast.

Creates a white (or black) border around an image that merges in with the image so that on a larger white (or black) background, the image appears to have a ragged border. This is similar to the Gimp's Fuzzy Border, but it adapts its jaggedness to the image. (Also unlike Fuzzy Border, it is deterministic, it does not depend on random number seeds.)

Some examples of what I mean by a jagged border that "adapts" to the image, which also illustrate the difference between a white and black border (it's not just the color), are shown in this triplet of images:

This script creates a series of V-Guides in the image at the user defined spacing. The user also specifies if the guides should start from the left, center, or right side of the image.

This script creates a series of H-Guides in the image at the user specified spacing. The user also indicates if the guides should start at the top, center, or bottom of the image.

A simple script that creates guides to border the canvas. The user is prompted for separate X and Y offsets.

A simple script that creates a horizontal and a vertical guide at the center of the image. The script is found under "Image | Guides".