Register Plus Redux is a WordPress plugin by skullbit and radiok that enables the user registration process to be customized in many ways.
Registration Enhancements include:
Customized registration page, including your own logo, disclaimer, license agreement, or privacy policy
User-entered password (with password strength meter)
Added profile fields
Additional required fields for registration
Invitation code system (with dashboard widget to track invites)
User-defined fields
Email verification of new users
Administration verification of new users
Customized new user message
Customized administrator message
Also includes fixes for known Register Plus bugs.
Register Plus Redux was forked from Register Plus, developed by skullbit, which was abandoned in 2008.
Download: http://wordpress.org/extend/plugins/register-plus-redux/