Wouldn't you want to create a workflow that (while it doesn't prompt the user for any added details) would allow you to add code to create the objects upon user registration / creation (or just afterwards, behind the scenes to the user)
It sounds like it would take a bit of custom extention / workflow development to build a (for example) eZCreateObject Workflow.
Watch out for a permissions problem when you do this. Theres a patch in the public mailing list but you have make sure your disable caching in your user templates. That 'ttl' line...