GIMP Plugin Registry

Radical Image Optimization Tool (RIOT for short) is a free image optimizer that will let you to visually adjust compression parameters while keeping minimum filesize.

It uses with a side by side (dual view) or single view interface to compare the original with the optimized image in real time and instantly see the resulting file size.  read more »

This script is meant to cut an image is smaller pieces and save these images automatically based on the size and names of specific layers, images to be used in web layouts.

Other options I found are based on guidelines. This approach has 2 drawbacks for me :  read more »

A Python plugin that exports a GIMP image as a Shockwave Flash file or the layers of an GIMP image as a Shockwave Flash animation. The package "swftools" is required.

Presented by familie redlich :systeme

Download, screenshot and more information at

http://my.opera.com/area42/blog/flash-swf-export-for-gimp

Creating XHTML source and cascading stylesheet from any Layer of the image. Supported features:

• Default font
• Background color, font color and link color
• clipping
• visibilty and opacity
• z-index and name
• position, width and height
• Text layers and text styles (requires Gimp 2.5.x or higher)

Presented by familie redlich :systeme

Download, screenshot and more information at  read more »

This plug-in changes colors in an image based on the HSV difference between two colors. This is particularly useful for applying color themes to existing images.
It avoids burning out high saturation and value at the expense of compression them somewhat when the difference goes towards higher saturation and value.
Current bugs/missing features include:
Undo does not work.
It can't be used on indexed images, even though it would frequently have enough colors.  read more »

Save for Web allows to find compromise between minimal file size and acceptable quality of image quickly. While adjusting various settings, you may explore how image quality and file size change. Options to reduce file size of an image include setting compression quality, number or colors, resizing, cropping, Exif information removal, etc.

If you want to send translations/contribute, please visit http://github.com/auris/gimp-save-for-web