laceous

Due to lack of interest (both my own and based on the number of downloads) this plugin will not be updated for WP 3.0
WordPress’ auth cookies include a built-in expiration date (either 2 or 14 days depending on if the ‘Remember Me’ option is checked). Even if you remove the client-side cookie (by manually logging out or just closing your browser if ‘Remember Me’ wasn’t checked when logging in) the data that was stored within the cookie is still valid until the expiration date is reached.
This could be an issue if someone managed to “steal” your cookie(s). They would still be able to access your website for some time into the future.
This plugin will immediately invalidate your auth cookies when you manually log out. This, of course, also means that you have to manually click ‘Log out’ for this plugin to work properly (you can’t just close your browser to remove any cookies that expire at the end of the session). This won’t prevent session hijacking, but should limit the amount of time that an attacker can access your website.

Invalidate Logged Out Cookies

This plugin will immediately invalidate your auth cookies when you manually log out.

prontotools

zkancs

Use a simple, single shortcode to allow your visitors to login or logout depending on their current status.
The shortcode outputs an a href link for you to add in the header, footer or anywhere else on your website.
Example Shortcode:
<pre><code>[login-logout text_to_login="Login" text_to_logout="Logout" class="custom-class" redirect="/shop/"]
</code></pre>
Available Parameters:
<ul>
<li>text_to_login – The text to prompt logged-out users to log in.</li>
<li>text_to_logout – The text to prompt logged-in users to log out.</li>
<li>class – Any optional custom classes to be added to the link.</li>
<li>redirect – An optional page to redirect to after logging in/out. If not included, users will redirect to whatever page they’re on when they click the link.</li>
<li>login_url – An optional parameter that user can change the URL login page</li>
</ul>

Login Logout Shortcode

A single shortcode you can place anywhere to allow visitors to login/logout.

Invalidate Logged Out Cookies vs Login Logout Shortcode