Question for Site designers

I'm looking for a solution for a site and hoped some of you designers could help me out. I'm creating a website, let's call it site. com and will have people sign up for their own site under mine which will automatically be created as a subdomain, I would like it to be added as web1.site .com and when they sign up they can choose from a few different layouts, and input their info easily.
It should also allow them to create up to 5 email addresses at the top domain site. com.
Anyone seen anything like this or have something like this. Any help is greatly appreciated.

Anyone??????