Could something like what Links SQL has be set up for just the user data? I think for the most part what people want to edit is information stored about the user... I think that if we could add fields and then they would become automatically available in the templates as $fieldname and then we could add the field to the profile and register form if we want them there...
If something like this was set up you could create so many hacks... private messages could be stored as one of the fields... ranks... etc.
Steven