Various enhancements are made to using smart cards that are associated with (or to be associated with) a household. In one embodiment, data that is expected to be of value to a user (e.g., electronic money) is attached to that user's smart card(s), thereby providing an incentive for the user to keep his or her smart card(s) secure. In another embodiment, the smart cards are used for parental control (e.g., by restricting the children's access to one or more of the smart cards). In yet another embodiment, smart cards are used to enhance user privacy by maintaining user-specific information on the smart cards (which can be de-coupled from the computing device whenever the user desires). In another embodiment, the boundaries of a network of computing devices are defined by multiple smart cards--any computing device to which a smart card is coupled is part of the network.