AJAX User Registration
to truly incorporate it into your site. It works great and will truly add to the professionality of any site, but may require some time to set it up.
The included setup script will allow the user to "hook" the form to your MySQL database that contains the user list inorder to add that user. Currently, the form only asks for username, password, and email address.
It might need to be configured to fit your personal requirements. The script is an intermediate level script.