Ryan Street

Show or hide content with a simple to use shortcode system. You can access or restrict content for:
<ul>
<li>Logged in/out users</li>
<li>different user types, (author, administrator, etc.)</li>
<li>different user roles and capabilities</li>
<li>URL Keys</li>
<li>password entry (good to show teasers, etc)</li>
<li>show/hide clickable links</li>
</ul>

Content Lock

Show or hide some or all of your content by wrapping it in convenient shortcodes!

Bryan Petty

Disables automatic post locking so multiple users can open the same post in 
the administration panel.
Warning: Post locking was an addition to WordPress in order to prevent such 
bugs as overwritten autosaves (coming from multiple authors), and of course 
to prevent accidentally overwriting another user’s changes with older content. 
These are often never problems for many users, and you should likely be 
communicating with your fellow editors when making changes anyway. This plugin 
makes the choice of relying on the latter rather than post locking, so you 
may run into those problems again.

Disable Post Locking

Disables automatic post locking so multiple users can open the same post in the administration panel.

Content Lock vs Disable Post Locking