1. A method for implementing and using a first sensory-interface device, the method comprising: providing a protective touch-sensor case having plurality of touch-sensitive surfaces that each have a plurality of touch-sensitive sensors; attaching the protective touch-sensor case to a first user's mobile device to form the first sensory-interface device, wherein the mobile device has a display visible on a front face of the first sensory-interface device, wherein the plurality of the touch-sensitive surfaces includes a first touch-sensitive surface on a back face of the first sensory-interface device, and wherein the first sensory-interface device is one of a plurality of sensory-interface devices each having a respective user; exchanging data between the protective touch-sensor case and the first user's mobile device; sensing touch of the first user on the protective touch-sensor case; training the first sensory-interface device to recognize a first gesture of the first user by having the first user trace the first gesture a plurality of times on the back face of the first sensory-interface device and developing a first set of reference information from a parameterized model of the first gesture; sensing and capturing a gesture made by the first user on the first touch-sensitive surface on the back face of the first sensory-interface device; comparing the captured gesture to the first set of reference information and, if the comparison is sufficiently matching, then generating a first personal authentication code that is personal to the first user based on the captured gesture; gathering data input from each respective user into each one of the plurality of sensory-interface devices for compilation into at least one of the plurality of sensory-interface devices; wirelessly sending the gathered data input among the plurality of sensory-interface devices based on personal authentication codes of the respective users of the plurality of sensory-interface devices; storing the gathered data input in a searchable database that is internal to the first sensory-interface device; and accessing and searching the database that is internal to the first sensory-interface device through a communications network.