New user, automatically new category for him/her

Hello,

when I’d like to set up a blog for a few users, using just one wordpress blog.
It should look out like this: user registers a new user and then wordpress has automatically created a new category for him/her. For an example, “Mike” registers and there’s a new category called Mike and when Mike writes a post then he can only write to that category.

There is that “Bind user to category” but then admin has to bind user to the category, I’d liked that made automatically when user registers.

Thank you!