I'm looking for a library that can handle user registration (name, address, e-mail etc.) into my existing WordPress website. What options exist today, or will I have to pull my own?
This is tutorial on extending user information I have stored in bookmarks: Adding and using custom user profile fields. Take a look and see if it fits your needs.
PS I am not following developments in user functionality closely so there might have been changes/improvements since tutorial was published.