30. A system comprising: a device comprising a display screen; and one or more computers programmed to interact with the device and to perform operations comprising: transmitting, from the one or more computers to the device, description data describing a preexisting structured presentation to be presented visually at the display screen of the device, the visual presentation of the preexisting structured presentation visually presenting information in a systematic arrangement that conforms with a structured design, the preexisting structured presentation denoting characterization of attributes of a particular instance by values that characterize the attributes of the particular instance by virtue of an arrangement of an identifier of the particular instance and the values in the visual presentation of the preexisting structured presentation; receiving, at the system, data describing user interaction with the preexisting structured presentation presented visually at the display screen of the device, the user interaction identifying a fraction of the visual presentation of the preexisting structured presentation for population with attribute values; and in response to the receipt of the data describing the user interaction, comparing characteristics of the identified fraction of the preexisting structured presentation with content of electronic documents in an unstructured collection of electronic documents to locate electronic documents that identify a new value that characterizes an instance characterized in the identified fraction of the preexisting structured presentation, adding the new value to the preexisting structured presentation to form a new structured presentation having at least the fraction of the visual presentation identified by the user interaction populated with new attribute values, and outputting instructions for visually presenting the new structured presentation to the device.
39. The system of claim 30 , wherein: the collection of electronic documents comprises the electronic documents available on the Internet; and the electronic documents comprise web pages.