Priyanka Bhave

This plugin adds login/ logout link in the navigation menu according to the user login status and then redirect to page/link set by admin and on click of login link a popup will open.
Plugin features :
<ol>
<li>Add login/ logout link to the naviation menu.</li>
<li>On click of login link Create a popup to login to the site.</li>
<li>Create a setting page for the admin to set redirection link after loggin/ logout</li>
</ol>
Steps to set redirection link :
<ol>
<li>Open the dashboard.</li>
<li>Click on login/ logout link under the settings menu.</li>
<li>Select the page or enter link to redirect after login/ logout for admin or non-admin login/ logout.</li>
</ol>

WP login/out link with login popup

This plugin adds login/ logout link in the navigation menu accordinng to the user login status and then redirect to page/link set by admin.

Nate Reist

This plugin simply adds a logout button to the content of any password protected post. Sometimes clients want a password protected page to share information with privileged individuals and the default 10 days for the cookie to expire is too long for their liking. So I wrote a little plugin to do this with AJAX and set the cookie to expire immediately, well actually 10 days in the past.
<ul>
<li>Works logged in or out as a WordPress user.</li>
<li>Uses the same functionality WordPress uses to set post cookies.</li>
<li>Has a simple settings page to make everything easier.</li>
<li>Allows you to alert user they have logged out.</li>
</ul>

Protected Posts Logout Button

Automatically adds a logout button to your password protected content.

WP login/out link with login popup vs Protected Posts Logout Button