foo_plorg is a simple component that will let your organize your playlists in a treeview fashion. It is available as either a Column UI panel or an UI element for the default UI. It enables your to create folders, hierarchies and move around folders and playlists by dragging and dropping them wherever you want in the panel.
This version REQUIRES foobar V1.1 (or newer) to work.
2.6, released on 2015-10-13