A module that allows user to create content anonymously, then if they register, assigns the content to them I recall a module I came across that was in dev a while back that basically allowed users to create nodes as an anonymous user. Then if they registered on the site, it assigned authorship of these nodes to that user account. Similar to how Drupal Answers works. It helps to lower the threshold for someone to get involved in a site. I just cannot recall the name.

Does anyone know?
You should use Create and Register module.


  This module creates a "lazy registration" which means that the user creates the content first and after this logs in or registers to the site.