A nice wordpress plugin
Enhance your Registration Page.
Custom Logo Tired of that WordPress logo getting all the attention? Upload your own custom logo image and get your brand in the spotlight.
Password Field Hate those forgettable auto-generated passwords? Allow your users to set their own prefered password during registration. Includes that sweet Password Strength Meter from the Profile page.
Invitation Codes Is your blog super exclusive? If so, you better require an invite to join your high end crew. Setup multiple codes and track where your new users are coming from with the optional Invitation Tracking Dashboard Widget.