You host on Dreamhost for the monthly cost and then ad your customer's domain name under your domain as a sub-domain? Which gives you control of their site that you design and maintain.
Well Dreamhost don't technically have "addon" domains. Dreamhost has their own control panel which THEY designed from the ground up and it's friggin' amazing, another reason I chose to host with them. Most hosting companies will offer cpanel with their shared hosting plans. GoDaddy has their own control panel but it SUCKS, very hard to use and understand, not intuitive; plus they just changed everything last year after I had finally figured out how the old one worked (one of the reasons I left GoDaddy). Dreamhosts control panel is SO easy to use, and yes there is a wizard to import cpanel settings if you're coming in from another host.
But getting back to your question, you wouldn't have an addon domain with Dreamhost because there is no primary domain assigned to your hosting account, you simply set up your account and then install however many domains you want, each with their own folder installed in your server space. I know my last two messages sound like I work for Dreamhost, but actually, I am just a seasoned consumer who has researched many of the large hosting companies and found the perfect one for my needs. Not saying their perfect for everyone, but for me they are.
Chad Spillars
"Look I finally made myself a signature!"