I'm not sure this goes in the 'openid_provider' or 'sreg' module, but I think it would be cool to allow the user to control which fields are exposed to the openid_provider and show those fields on the openid page of the user.

Myopenid does this very well: it allows multiple personas to be defined, each with potentially distinct usernames, emails, etc.

To begin with, just choosing which parts of the user profile could be considered sufficient for this feature request.