In case you (or your clients) are running wordpress blog, we recommend that you use the plugin:  HC Custom WP-Admin URL  , as a security measure/good protection, against wordpress attacks at the admin url or admin login page.

http://wordpress.org/plugins/hc-custom-wp-admin-url/

*** Please use any words other than wp-admin , admin or administrator , for better protection against automated attacks on wordpress admin login page.

*** Please use a very strong admin password and do not use the admin username as admin or administrator, use custom administrator user names of your choice while installing wordpress
WordPress admin username changer
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http://wordpress.org/support/view/plugin-reviews/admin-username-changer
http://wordpress.org/plugins/admin-renamer-extended/ 

This is for blogs that allow other users to register to their blog:
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http://wordpress.org/plugins/restrict-usernames/

*** Please note that before installing/using any plugin, please make sure that you take a backup of the wordpress database as well as the web pages/wordpress files.
*** Before installing a plugin, please  check if the plugin is compatible with your wordpress version.