This functionality is not support .  What you are really talking about is user customizations and the ability to persist any changes they make to the layout now matter where the access the site.

Yes, you could create child portals for each user and make the user the admin of the portal.  I have heard of some sites that have taken this approach,   Just remember, at some point you might reach a limit to how many portal you can have.  If this is a small site and a set numer of user this should not be an issue. 

After further thought you could also setup a seperate page for each user and give each user edit rights to their page.  Then on thier page they would be able to add content to thier page any way they want to (just like a site admin can, but restricted to thier page).

You could also do a combination of this and create child portal for different groups/departments and then under each child create the individual users page under the appropiate child portal.