Subhransu Sekhar

When you login to wordpress site it saves the auth info in cookies which have a expire time of 2 days. If some body get access of your cookie he can get into your wordpress iste. Use this plugin to increase the security by adding some random variable in the cookie for validation.

Safe Cookies

Secure your wordpress site by making the Auth Cookie more secure

tronhammer

This plugin will mimic a keep-alive ping by utilizing jQuery to perform an ajax request to the current page, which will update 
the session token tied to PilotPress and or any other system attached using PHP built in sessions. Session Slap will also provide 
a settings interface to allow admins to configure details relating to interval amount (which is defauled to 5 minutes less than the 
session.maxlifetime set in php.ini).
A few notes about the sections above:
<ul>
<li>Configuration options are available in the Settings -> Session Slap menu.</li>
<li>Updates built in PHP sessions only.</li>
<li>Attempts to access session.maxlifetime ini settings, but will default to 24 minutes if not available.</li>
</ul>

Session Slap

Session Slap mimics a keepalive ping by making an AJAX request to the current page to refresh active session timestamp.

Safe Cookies vs Session Slap