Blender won't import my custom module, ImportError: No module named mymodule My addon is in /home/usr/.config/blender/2.68/scripts/addons/foldername, has an __init__.py and cannot somehow import parts, that exist in the same folder. It says, 
no module named mymodule but from text editor it runs and work properly

What could be wrong here?
You can place your module into the folder blender_directory/2.68/scripts/modules/ (so Blender can found it automatically), while your addon can stay in the scripts/addons/foldername folder with its __init__.py (and not __index__.py, by the way).

Or, you can go to User Preferences, tab File, and specify a custom extra folder for scripts, in the scripts input.
Note that this custom folder must contain 3 sub-directories : addons, modules, and startup.



In this example, your addon will of course be placed in :
/home/user/scripts/blender/addons/yourAddon/,
and the module(s) you want to import will be into :
/home/user/scripts/blender/modules/.

This way, no need to use sys.path.append()!