Abstract: Augmented-reality systems provide additional information to users, beyond what they can normally perceive with their own senses. Embodiments of the invention establish “cover objects” having an identifiable visual appearance, and provide systems and infrastructure to deliver the additional information to multiple users via a live digital-camera image when each user directs his or her camera at the cover object. Different users may receive different additional information when scanning the same cover object at the same time, and a single user may receive different additional information when scanning the same cover object at different times. Methods and systems for accomplishing this are described, and a number of applications using the capabilities of such systems are suggested.