Not sure if this post should actually go in the other forum, but here goes...
(Note that the paper sizes are UK/European ones.)
I use standard foolscape manilla half-flap "wallet" folders for all my paper filing at work. In addition to these, I've found a use for the simple square-cut "fold-in-half" folders. I don't normally like these, as paper can fall out of them too easily, but with a little trimming they can be used inside a "wallet" folder, to give you a sub-folder. Uses are left to the imagination of the reader; I've found several