In MAC OSX, stacks is used to represent conetents of a directory. This a 1D (array) and the number of files that can be shown is restricted. So, if file number is larger, it shows in a tradition box. Instead of a box if we use a tree structure, we can use 2D space. We use branches to even distinquish between file types/alphabets/time/size/etc. Sorting can be done in multi level using sub-branches. Directory inside the current directory will be shown as leaf. But when clicked, can be expanded as a branch.
Nice animation can be used to show a tree groing and leaves forming after the palsmoid button is pressed. This can be used as desktop folder view which can grow leaves as someone copies file(s) into desktop directory/drops file(s) on desktop. delete drops the leaf and small animation showing leaves collected into garbage bin.
With a proper animating wallpaper showing day and night transition, this will look like a real life equivalent of tree
.