15. A content similarity-based social network establishment method, comprising: providing a content analysis means configured as device-executable code stored at a non-transitory data storage medium; providing to two or more validly-registered entities a social networking graphical user interface (GUI) as device-executable code stored at a non-transitory data storage medium and configured, when executed by data processing circuitry, to cause a display device operably coupled with a viewer's network-coupled device to display a shared window including a first content display portion, a second content display portion, and a linked-user portion, wherein: the first content display portion is operably coupled with the content analysis means; the first content display portion is configured to display content to a viewer concurrently with and in the same manner as does the second content display portion, and the linked-user portion is configured to display an identification of each linked-user and a miniature image of content with which each linked-user is engaged; detecting an engagement with first viewer-perceivable content at a network-coupled device by a first validly-registered entity of the two or more validly-registered entities; analyzing the first viewer-perceivable content by the content analysis means; identifying one or more characteristics of the first viewer-perceivable content; analyzing, by the content analysis means, second viewer-perceivable content concurrently engaged in at a remote network-coupled device of a remote second validly-registered entity of the two or more validly-registered entities; identifying one or more characteristics of the second viewer-perceivable content which are either the same as or similar to the one or more characteristics of the first viewer-perceivable content; linking the first validly-registered entity into a live, interactive social networking construct with the second validly-registered entity; and rendering the first viewer-perceivable content concurrently perceivable at the first content display portion of the social networking GUI of the network-coupled device and at one of the second content display portion and the linked-user portion of the social networking GUI of the remote network-coupled device.
15. A content similarity-based social network establishment method, comprising: providing a content analysis means configured as device-executable code stored at a non-transitory data storage medium; providing to two or more validly-registered entities a social networking graphical user interface (GUI) as device-executable code stored at a non-transitory data storage medium and configured, when executed by data processing circuitry, to cause a display device operably coupled with a viewer's network-coupled device to display a shared window including a first content display portion, a second content display portion, and a linked-user portion, wherein: the first content display portion is operably coupled with the content analysis means; the first content display portion is configured to display content to a viewer concurrently with and in the same manner as does the second content display portion, and the linked-user portion is configured to display an identification of each linked-user and a miniature image of content with which each linked-user is engaged; detecting an engagement with first viewer-perceivable content at a network-coupled device by a first validly-registered entity of the two or more validly-registered entities; analyzing the first viewer-perceivable content by the content analysis means; identifying one or more characteristics of the first viewer-perceivable content; analyzing, by the content analysis means, second viewer-perceivable content concurrently engaged in at a remote network-coupled device of a remote second validly-registered entity of the two or more validly-registered entities; identifying one or more characteristics of the second viewer-perceivable content which are either the same as or similar to the one or more characteristics of the first viewer-perceivable content; linking the first validly-registered entity into a live, interactive social networking construct with the second validly-registered entity; and rendering the first viewer-perceivable content concurrently perceivable at the first content display portion of the social networking GUI of the network-coupled device and at one of the second content display portion and the linked-user portion of the social networking GUI of the remote network-coupled device. 22. The method of claim 15 , wherein the content characteristics include one or more of metadata, form, structural elements, sequence of structural elements, context, and subject matter of the content, and either alternatively or additional including one or more of an object, marker, data packet, and visual representation of code, either inserted or overlaid relative to the presented content.