I'm looking to create a 'Last Updated' field in a user's profile. I was then going to create a rule that filled that field with the current date everytime the user's profile was edited. I want the information for admin purposes and don't want the user to see this info.
Is this possible? I'd prefer not to use a module.
EDIT: I would be fine with the field being on the user-edit page instead (but still hidden) if that's easier.