Create subdomain dynamically

Hi all,

Quick question, I am on shared hosting, and would like to know if it is possible to create subdomains dynamically, ie :

[]User fills a form to create a profile
]Subdomain is created
Domain can be redirected, mirrored or hosted. All works![/quote]

An alternative I think about is using DNS, so without ever creating all these subdomains:

[]Visitor types
[]Visitor is redirected to
Something like the first answer here but I am not familiar enough with DNS to know[/quote]