I believe Burst2flame is asking for something else, not the built-in password protected area.
This process is infact a reverse of WP built-in password protected area. It would be some kind of simplified data base that:
User go to the log-in page –> Key-in a password –> The page transfer to a link respectively to the password.
I’m also looking for something similar to him to put in my blog. But so far I have searched through 600+ WP plug-ins and have no luck 🙁