John P. Bloch

Create child themes from any non-child theme with the click of a button.
This plugin is multisite compatible; if used on a multisite network, controls for creating child themes will be in the network admin instead of the regular site admin. Pick the parent theme from the dropdown and name name your new child theme. You can also change the author name and select files you want to copy from the parent to the new theme.
Click the button and you’re all set!

Child Themify

Create child themes with the click of a button.

jeff.cave

This plugin provides a “Sub Page” widget. It lists all of the pages which are children of the current page. If there are no children, it will not display.
Options include:
<ul>
<li>title (obviously)</li>
<li>“No Sub-pages” text instead of blank (configurable)</li>
<li>hide widget when no sub-pages</li>
<li>show siblings when no sub-pages</li>
</ul>
While this is a small widget, I have attempted to make this as configurable as possible, with clean and efficient code (this is a small widget, and shouldn’t slow your site down).

PS Sub-pages

Shows the child pages of the current page. Configurable title, show siblings (or not), and "no child" text

Child Themify vs PS Sub-pages