What would that script be called? I've tried "free hosting script" but it didn't yield good results. To make your site so that people can sign up and make their own site in a subdomain.
1) You get permission from your host to do that. 2) When you find out that you can't do #1, you forget about finding a script. Some hosts allow you to sell (or give away for free - that's your decision) subdomains of your domain - and provide the control panel for you to do it with. Others just won't allow you to do it. (Even if you do, they'll delete what you do, and your "customers" won't have sites.)