A while back I had come across a novel method for increasing local contrast and details in an image by German artist/photoshop guru Calvin Hollywood. He called it "Freaky Details", and it basically consisted of an inverted duplicate of the base image that was "Surface Blurred", and had the blend mode set to "Vivid Light".
Unfortunately at the time, I didn't have access to a "Vivid Light" blend mode in GIMP, and wasn't sure how "Surface Blur" worked in Photoshop.
This simple script auto offsets all layers to the selected layer along the X and Y direction. By now it does not respect Layergreoups in the correct way, but I guess this will be a great help when working on sprite sheets. You are also free to flip the mapping direction of each axis. Let me know if there are bugs or if you need some more options for this. Hope this will be helpful. :)
You find the tool in the file->create Menu
Rather than using the regular procedure browser to look up the documentation for a procedure, you can use this help() replacement. Here is a sample of the output for the plug-in-tile procedure:
plug_in_tile(image, drawable, new_width,
new_height, new_image, run_mode=RUN_INTERACTIVE)
This style is usually widely used as a style of pop art artist, perhaps a bit we added highlights with contrasting colors will produce dramatic works of pop art. For more details see here. http://youtu.be/wBKRxv_4YA0
From the same 'meetthegimp' thread as the previous poster, patdavid, but my version is sufficiently different to merit a post of its own, I think.
Should work in Linux and Windows and have a few more options so had to rework the dialog to barely fit on my Windows portable!