Is it possible to have album.php display all the thumbs of a subfolder on the main view?

This way I can show all thumbnails on the main page, and treat subfolders as "filter categories".

You surely know that "is it possible" is really the wrong question for coding. Everything is, just a matter of time, knowledge and - sometimes - money :-)

Yes, you are correct there! I just haven't figured out how to dive into those subfolders quite yet!