Write a post before signup?

Has anyone an idea how to enable people to write a post before they are signing up? Similar to the q&a plugin. It works well with it but instead of a question I want the user to be able to write a short blog post before being asked to sign up.

This should also work with ultimate facebook to make it easy for users to sign up (it does work with the Q&A plugin)

Any pointers would be awesome!