OpenID works also for offline forms
An OpenID user is asked to fill an empty paper form with personal data (at the gym, at the bank, at the video club, etc).
He just needs to fill the OpenID field and asks the Form Owner to just request online OpenID details for his user.
The Form Owner goes online and submits OpenID a request for personal data for that User.
User receives the request, indicating the fields the Form Owner needs, and he accepts or denies them.
Form Owners could also be warned when User changes any of those personal data.