A general purpose high-pass filter plugin. It shows up as Filters->Generic->High Pass Filter. You can select a blur radius that sets the size of detail to be passed by the filter, as well as an option to keep the source layer or replace it.
EDIT: Updated to use grain extract rather than the previous method, This looses less histogram data and is closer to the Photoshop version...
It actually implements 5 different high pass modes:
Python-Fu script to apply light bloom effect on an image. Simply put, this script will make shiny parts of the image even shinier and makes the light creep over the edges of darker objects, sort of like what usually happens when you take a photo against the light. The script will create a flattened copy of the image, and add a layer of light on top of it. You can play with the growth settings in the script and the layer opacity and mode to achieve certain effects.
exposure-blend makes quick work of blending 3 bracketed exposures into a detailed, realistic, extended contrast image. It has many features to save you the drudgery of assembling contrast blended stacks yourself:
'watermark' by Doug Reynolds allows the user to add text as a watermark into an image. The watermark text is done as a lighter overlay of the background of the image. Besides the text itself, the user can choose the font from a pull-down menu, size (in pixels), location (one of the four corners), and opacity (in percent).
After installation the plugin script is availbe under the menu: Script-Fu/MyScripts/Watermark.
This program creates stereoscopic 3D anaglyph photos from a stereo pair. In order to make use of this program you will first need a pair of images from slightly different angles or the same object. You then need to place both images as different layers in the same image window in Gimp with the right image as the Bottom layer and the left image as the next layer above it and no other layers in the image (if you use this script in other circumstances then it probably won't work properly).
Posting this picture filter here specially because it's very rare and difficult to find picture filters made as plug-in for Gimp coded in Python - publishing this would be also for encouraging people on enrich Gimp with good filters (better than mine one, please! :-D )
The only problems of this filter is it seems to be somehow slow (even having a simple code), wich takes 20 seconds with a 320x200 picture - it's also missing undo and progress bar while running...