1. A computer-implemented method performed by a computer for determining a topical influence value of a commentor, an influence value of an individual and a topical influence value of a web-site, wherein the computer is in communication with a server via network to access a web-site hosted by the server, the computer-implemented method comprising steps of: matching and tagging content within the web-site with a selected topic, using a processor of the computer, to generate tagged content; extracting, with the processor, viral properties for the tagged content; identifying, with the processor, a commentor from said tagged content and an individual cited in the tagged content contained within the web-site; aggregating, with the processor, the viral properties for the tagged content from said web-site to form aggregated viral properties of the tagged content from said web-site, the viral properties of the tagged content from said commentor to form aggregated viral properties of the tagged content from said commentor, and the viral properties of the tagged content citing said individual to form aggregated viral properties of the tagged content citing said individual; computing with the processor: the topical influence value of said commentor based on a linear combination of the aggregated viral properties of the tagged content from said commentor weighted with respective weights applied to each of the aggregated viral properties of the tagged content from said commentor; the influence value of said individual based on a linear combination of the aggregated viral properties of the tagged content citing said individual; and the topical influence value of the web-site based on a linear combination of the aggregated viral properties of the tagged content from said web-site, the topical influence value of the commentor, and the influence value of said individual cited in the tagged content.