Note: German versions of this article can be found here and here.
One of my favorite features of Photoshop if the feature "Save for web". Its a nice tool to optimize your image for the web. You can basically choose file format, compression, number of colors and see the results of the optimization in a preview image.
In Gimp there is no such feature by default yet. But there is a plugin that implements the feature. You can download it here.
After installation the plugin becomes available in the file menu. The plugin offers the same functions as the Photoshop one:
Installation on Windows
On Windows you just extract the .exe file of the plugin into the plugin directory of Gimp: c:\Users\username.gimp-2.8\plug-ins.
Installation on Linux
After extraction of the archive on Linux the installation is done in three simple steps:
./configure
make
make install
However there where a few problems with that. The configure script exited with an error message:
configure: error: Package requirements (gimp-2.0 >= 2.3.0 gimpui-2.0 >= 2.3.0) were not met:
No package 'gimp-2.0' found
No package 'gimpui-2.0' found
This looks like Gimp could not be found, but thats not true. Actually you need the gimp2.0-dev package installed:
sudo apt-get install gimp2.0-dev intltool
In my case it also needed the package intltool. After that the installation steps went without no further errors.