Peter Wooster

This plugin allows authors to restrict the users’s access to individual pages, posts and menu items based on the user’s logged in status.
Features for Authors
<ul>
<li>You can restrict pages and posts while editing by using the “Simple Access Control” widget.</li>
<li>You can set the message displayed when a visitor accesses a locked page using the “Simple Access Control” item in the Settings menu</li>
<li>The locked status is shown in the admin page and post lists</li>
<li>a “Loggedin Text” widget is available that only displays text to logged in users</li>
<li>You can set an option to display the menu even when filtered</li>
<li>You can set an option to force a 404 Not Found error on direct access to a restricted page</li>
</ul>
Features seen by users
<ul>
<li>Locked pages and posts are not displayed</li>
<li>Locked items are removed from standard and custom menus</li>
<li>A message asking you to log in is displayed if you access it directly using its address or using the next and previous links</li>
<li>A 404 Not Found error may be displayed on access to a restricted page</li>
<li>A login/logout link is displayed in the mesage</li>
<li>Loggedin Text widgets are not visible</li>
<li>Pages and posts can be hidden from either logged in or not logged in users </li>
</ul>
Additional Features
There are no additional features supported by Simple Access Control. The code is simple, small and well documented, 
so you can use it as a starting point for your own access control plugin.

Simple Access Control

Well thought out -- uses filters to hide selected pages and menu items.

A bit more documentation would be nice though -- it took me a while to find the extra check boxes on the right hand side of the post/page editing form.

Excellent

A very simple plugin that hides specific pages, posts and menu items from users based on their logged in staus.

zweidesign

This WordPress Plugin transforms children pages into OnePager sections of their respective parent page.

OnePager for WordPress

This WordPress Plugin transforms children pages into OnePager sections of their respective parent page.

Simple Access Control vs OnePager for WordPress