Extension: Multi Page Forms
Multi Page Registration Form extension allows you to turn your registration forms into multi step pages with previous and next buttons. Last page submits the registration form. Name pages separately and show them above the registration form fields.
WordPress Registration Plugin
Multi Page Registration Form Extension is part of RegistrationMagic Gold. Note that RegistrationMagic extensions are part of bundles; extensions are not available (or sold) individually.
This Extension is available here.