There's
http://www.webmin.com. But I imagine the setup for this product would be over and above that for Apache itself.
/etc/httpd/httpd.conf (Apache's config file) isn't too complicated. For virtual hosts (name based), there's an example at the very end of the file. Just uncomment it and add your own section like:
NameVirtualHost *:80
and for each virtual site:
<VirtualHost *>
ServerName www.<NAME>.com
DocumentRoot /path/to/htdocs
ErrorLog logs/path/to/error_log
CustomLog logs/path/to/access_log common
</VirtualHost>
There are other parameters you can place in the Virtual host tags.
http://httpd.apache.org/docs/vhosts/index.html
After you edit httpd.conf, you need to restart Apache, either by stopping and starting in System Preferences, or by using "apachectl" in /usr/sbin like:
/usr/sbin/apachectl restart
as the root user.