It would be great to have the ability to have field security based on the owner of the record.
Ex: If i'm the owner of the contact, I can read the e-mail adresse, otherwise i do not see it.

Also based on the record status, for approval process.

Ex; I cannot change values, when a record in a to be approve status if not I can modify it. Just disabling the field is not enough, because some tools overrides the screen customization.