shoreline - 2:53 pm on Apr 13, 2013 (gmt 0)
You can also add the following to your htaccess file inside your public_html directory which will then protect all the Wordpress websites under that folder.
Only catch is, if your IP address changes, you'll need to modify that one htaccess file before you can log into your Wordpress sites. Small price to pay for additional security of many Wordpress installations.
Deny from all
allow from 126.96.36.199