I expect my friends & family would really appreciate the opportunity to join my social graph (or is it a 'chart' in the medical context) in yet another context.
Here I start the sharing process.
I choose who I want to share my health info with (in this case myself) by providing an email address.
I am given intuitive and informed control over the specific types of information to be shared. There is just the right level of detail. Why just the other day I was trying to share my 'Hb1ac' levels with my hockey team. I decided against giving myself 'custodian' permissions as I feared I'd be expected to mop the clinic floors.
HealthVault sends an invite to the email address.
I get my invite from HealtVault. I am warned about 'phishing' (I am not warned about Big Pharming).
If I accept the invitation I am encouraged to create my own account at Healthvault.
Perhaps it is appropriate for a health site to rely on viral marketing methods.