ruudkok

Don’t keep logging in to your WordPress admin panel over and over again. Install this plugin to remain logged in to your blog for up to a year (unless you log out manually).

WP Keep Me Logged In

This plugin will increase the session time of your WordPress login cookie to 1 year. That way you won't have to login over and over again.

atdev

The phpMyDirectory WordPress plugin allows wordpress users to log into phpMyDirectory. The plugin is configured in the WordPress admin area.
Users only need to log in once and they will be automatically logged into phpMyDirectory. This allows phpMyDirectory to be used alongside WordPress and for a directory to be easily created for WordPress.

phpMyDirectory

Allows wordpress users to automatically log into phpMyDirectory.  The sessions are shared and accounts are created automatically if they do not exist.

WP Keep Me Logged In vs phpMyDirectory