Possible change to help make piwigo even better. It might be nice to implement a system similar to the Album menu the users see on the main gallery page with the Add/Delete Permalinks for the administration panel. This really comes into play when you are dealing with a gallery with over 300+ Albums.
The ability to expand/collapse an Album / sub-Album would make navigation a lot easier. These are just little things I am noticing as I work with the software and migrate 8000+ photos.