1. A system comprising: a non-transitory computer readable medium; and program instructions stored on the non-transitory computer readable medium and executable by at least one processor to: maintain an attribute-association database comprising data for a set of data items, wherein the data for a given one of the data items specifies, for each of one or more attributes from a set of attributes: (a) an associative value that indicates an association between the attribute and the data item and (b) a temporal-decay value that is decreased at a pre-determined rate over a period of time during which the first data item is not accessed; detect an event corresponding to proximity of a first user-information device to an entity associated with a second user-information device, wherein the event is associated with one or more event attributes from the set of attributes, wherein detecting the event comprises: receiving input data, wherein the input data comprises sensory-input data wherein sensory-input data comprises data that is received from at least one of microphones, camera, accelerometer, gyroscope, compass, electrodes, shock sensor, chemical sample or analysis system, biological sensor, ambient light sensor, thermal sensor, pressure sensor, and humidity sensor; and identifying at least one event attribute associated with the event based on the received input data; in response to detecting the event corresponding to proximity of the first user-information device to the entity associated with the second user-information device: determine a relevance of a given one of the data items to the detected event based on: (a) the associative values that indicate the association between the event attributes and the given data item and (b) the temporal-decay values; select at least one data item, wherein the at least one data item is selected from a set of the data items based on the respective relevancies of the data items in the set; and provide an indication of the at least one selected data item via at least one output device.