At first look DocusTree (version: 3.2) might look like a notes organizer. The interface and look is of the two pane outliner or organizer where the focus is on writing, jotting down and inserting various media or documents. While this is true of DocusTree it is more geared towards organizing existing documents or websites in a central location.
As the demo (see screenshot) shows when right clicking on a node DocusTree is mostly about adding. Of course a user can include a new document and start typing – for keeping a list for example – but this freeware is built