alfaguru

This plugin provides similar functionality to the <a href="http://drupal.org/project/sidecontent" rel="nofollow ugc">Drupal Side Content module</a>.
It enables you to define a set of widgets which are effectively placeholders. Each one is empty until you assign content 
to it when editing a page. 
This enables you to extend the content of the page into the sidebar.
Suppose, for example, you have a set of pages about people in your company. You could use a side content 
widget to add a biography for each of them, or a photo, or to list their favourite pizza toppings.
You can use the plugin without any template changes at all, but it does provide a simple API so you can test for the presence of side content widgets and adjust your templates accordingly.
As of release 0.7 of the plugin, it supports the <a href="https://codex.wordpress.org/Shortcode_API" rel="nofollow ugc">WP shortcode API</a>. There is also an extra add-on plugin which provides the same support for <a href="http://alexrabe.boelinger.com/wordpress-plugins/nextgen-gallery/" rel="nofollow ugc">NextGEN Gallery</a> shortcodes (development sponsored by <a href="http://www.comunicrea.com/" rel="nofollow ugc">Comunicrea s. n. c.</a>).
Release 0.75 fixes a bug affecting side content widgets with names containing characters other than lowercase alphanumerics. A new contributed extension provides integration with the qTranslate plugin.
Release 0.8 adds no new functionality but makes the plugin compatible with WP 2.7. 
Release 0.9 adds no new functionality but makes the plugin compatible with WP 2.8.1. 
Release 1.0 adds no new functionality but makes the plugin compatible with WP 4.1.0.
<h3>API</h3>
Use the following code to test for the presence of side content widgets:
<pre><code><?php if(function_exists('the_side_content') && the_side_content()->has_widgets() :?>
</code></pre>
Use the following code to test for the presence of a particular side content widget called ‘widget name’:
<pre><code><?php if(function_exists('the_side_content') && the_side_content()->has_widgets('widget name') :?>
</code></pre>
The plugin defines a filter, ‘side_content’, which can be used to preprocess side content widgets before display.

Side Content

Side Content enables you to create widgets which have different content on different pages.

Martin Tod

A quick way to show a set of the pages in a particular part of your site without having to show all the pages on the site.
Adds a widget to let you show a clickable list of pages linked to a particular ‘parent’ page on your site.

Sub Page Hierarchy Widget

An easy widget to let you show a clickable list of pages linked to a particular 'parent' page on your site

Side Content vs Sub Page Hierarchy Widget