Sean Fisher

This plugin will hide WordPress Admin (/wp-admin/) when a user isn’t logged in. If a user isn’t logged in and they attempt to access WP Admin directly, they will be unable to and it will return a 404. It can also rename the login URL.
Also, you can add HTTP authentication directly from WP Admin and add custom username/password combinations for the HTTP auth or use the WordPress credentials.
This doesn’t touch any .htaccess files or change the WordPress core files. All the CSS/Images under /wp-admin/ are still accessible, just not the .php ones.
If you enable HTTP authentication, it will add HTTP authentication to the PHP files in /wp-admin/.
To contribute to the development, check out <a href="https://github.com/srtfisher/Lockdown-WPAdmin" rel="nofollow ugc">the GitHub Repository</a>.

Lockdown WP Admin

Lockdown WP Admin conceals the administration and login screen from intruders. It can hide WordPress Admin (/wp-admin/) and and login (/wp-login.

ColinHunt

Demo Lock is a fully configurable plugin for WordPress developers that aims to provide a secure environment in the wp-admin interface enabling users to test admin interface plugins in a live demo with extremely limited access to all other WordPress settings. This is a heavily modified version of a plugin originally written by Thomas Griffin (http://thomasgriffinmedia.com/blog/2012/08/create-live-demo-wordpress-plugin/). It has been modified to 
be completely plugin-independent and fully customizable through the config.php file, and updated to WordPress 3.5 standards.

Demo Lock

Demo Lock is a fully configurable plugin for the wp-admin interface enabling plugin developers to…

Lockdown WP Admin vs Demo Lock