Yet another high pass. I use it to normalize brightness of textures. This script provides two different approaches: grain extract mode (mainly used to remove the effect of vignettes) and soft light mode (for images with sharp lightness transitions, but this mode is not so powerful as grain extract).
After installing, you'll find it in:
Filters/Enhance/High Pass Filter
Script produces new layer and sometimes you need to change levels manually (yes, this is not "make it cool" button!).