I think it was Megrain who suggested Joomla on an earlier post in this thread. I've been using it with two sites so far, one primary domain in my web root (i.e. /var/www/html) and one virtual domain in the virtual web root (i.e. /var/www/virtual/virtualdomain_name.com). All websites can be added to the web server in the webconfig. The first entered becomes the primary and any entered thereafter become the virtual sites (as many as you want if your server can keep up). Of course each virtual domain requires a registered domain themselves. Subdomains to your pointclark.com domain won't need to be registered domains, but they will need to be added in your Clear Center account. Any new domains you want to register can also be done in your Clear Center account. You'll want to create aliases for any registered domains for virtual sites (unless you have muliple static ip addresses from your isp) by way of cname records. These cname records will point the domain names for your virtual sites to the same ip address of your primary domain. Works like a charm.
Now, once all this is done, you just copy all the contents Joomla includes in their installation package into the webroot. Do the same for every virtual site you're hosting into the virtual webroot(s). I recommend you copy and rename the configuration.php-dist file to configuration.php and delete all the script from it, so its basically a blank file. Don't worry, Joomla will populate it with script during the configuration steps. Before doing the next steps, you'll ideally want to give apache ownership of your webroot:
chown -R apache:apache /var/www/html
and the same for virtual sites:
chown -R apache:apache /var/www/virtual/virtualdomain_name
To configure Joomla for each site you then enter the site's address/administrator and Joomla will walk you through the rest. After the initial configuration you'll be required to delete the installation (it's literally labeled "installation") folder from your webroot before you can proceed any further. Once you do that, you can get into the backend administration panel using the default username of "admin" and the password you assigned during the initial configuration. It's pretty straight forward after that. Just take your time during the initial configuration and check all the fields that need entries. I recommend you install the sample files during the configuration process because it will make startup so much nicer for you.
Any customers of yours that want to configure and design their own (Joomla) sites can then have usernames and passwords configured for them and be made superadministrators for the site(s).
It really is good stuff.