thewebist

A widget for displaying a list of subpage links. The list remains consistent regardless of where you are in the hierarchy.
Other features include:
<ul>
<li>Widget displays only on pages with subpages or on subpages.</li>
<li>List title is a link to the main page parent.</li>
<li>You can specify the link text for the list title, or you can completely hide it.</li>
<li>Sort subpages by Menu Order or Page Title.</li>
<li>Specify the depth of pages shown (all in hierarchy, all in flat list, 1 level, 2 levels, etc.)</li>
<li>Presentation utilizes minimal markup to allow for easy styling via your theme’s CSS.</li>
</ul>

WenderHost Subpages Widget

A widget for displaying a list of subpage links. The list remains consistent regardless of where you are in the hierarchy.

macnetic-labs

NF Subpages adds pages and fieldset elements to the ‘Layout’ Elements’ block. It also includes labels and custom classes for elements to allow for more interesting layouts and styling. Subpages works only with javascript, otherwise it displays the pages with fieldsets.
This plugin requires the Ninja Forms plugin.

NF Subpages

NF Subpages adds pages and fieldset elements.

WenderHost Subpages Widget vs NF Subpages