Disable Main WordPress Network Site


I have begun using some of your extensions for WordPress multisite and so far everything is working great. My question is specifically around how to disable access to the main install of WordPress multisite.

For example, my core WordPress installation is at http://my.network.com and the multisite installation is setup to use sub-subdomains for example http://wpmu.my.network.com.

In the example above, I only want to disable the frontend/public access to http://my.network.com but all the sub-subdirectory installations via WordPress Multisite should continue to work.

One idea is to create a theme that renders just a blank page. Any other real ideas besides this?