Joomla-User-Reregister is a project mainly written in PHP, it's free.
This script is for replication the activation setups for a user in the joomla 1.5 system.
What if you are just migrating all the users from you awesome forum software from the year 2000 to a joomla system, or you suspect a not so nice person dumped your database file and you want to make all your users change thier passwords.
This script is designed to be run from the commandline
///// php reregister.php ////
Zip the plugin folder and install. The force password plugin is a direct download from http://www.sourcecoast.com/extensions, no changes were made to the pluginat all.
place reregister.php to root of your joomla install and run.
This could have been a component or something but it seems to be kinda a one off script so i did the bare minimum.