Create Layer Mask from...

GIMP 2.8 Python Plugin.
This plugin allows you to create layer mask from another layer mask.
Or create layer mask from grayscale copy of layer.

In addition, the main feature of this plugin - is an option that allows you to change the interaction between two masks (Replace, Subtract...):

Installation Instructions:
1. Extract "create-layer-mask-from.py" from .zip archive to the ".../.gimp-2.x/plug-ins/" directory.
2. Make sure that the extracted file is executable.
3. If you are already running GIMP, close and reopen it.

This plugin requires Python!
If you have the "Filters > Python-Fu > Console" menu item you are all set. If not, install Python support for GIMP.

Download:
Download from my site with some gimp plugins:
some-gimp-plugins.com

Version History:
v1.0 (30.08.2012)
- Initial release.

My other plugins:
Scale Layer to Image Size
Layer via Copy/Cut
Duplicate to another Image