15. A comment association system for associating one or more comments with one or more primary electronic documents, the comment association system comprising: a processor; and a memory coupled to the processor, the memory storing processor executable instructions which, when executed by the processor cause the processor to: identify one or more key terms from at least a portion of the one or more primary electronic documents; identify one or more comments associated with the identified key terms; wherein identifying the one or more comments comprises: determining a measure of the likelihood of a key term and a marker being found together in a comment; and determining whether the measure of the likelihood of a key term and a marker being found together exceeds a predetermined threshold and if so, identifying comments containing the marker; determine whether an identified comment is sufficiently related to the one or more primary electronic documents by calculating one or more relation score for that identified comment and comparing the one or more relation score to one or more threshold; and if the identified comment is sufficiently related to the one or more primary electronic documents, then associating the identified comment with the one or more primary electronic documents.
15. A comment association system for associating one or more comments with one or more primary electronic documents, the comment association system comprising: a processor; and a memory coupled to the processor, the memory storing processor executable instructions which, when executed by the processor cause the processor to: identify one or more key terms from at least a portion of the one or more primary electronic documents; identify one or more comments associated with the identified key terms; wherein identifying the one or more comments comprises: determining a measure of the likelihood of a key term and a marker being found together in a comment; and determining whether the measure of the likelihood of a key term and a marker being found together exceeds a predetermined threshold and if so, identifying comments containing the marker; determine whether an identified comment is sufficiently related to the one or more primary electronic documents by calculating one or more relation score for that identified comment and comparing the one or more relation score to one or more threshold; and if the identified comment is sufficiently related to the one or more primary electronic documents, then associating the identified comment with the one or more primary electronic documents. 22. The comment association system of claim 15 , wherein identifying one or more key terms comprises: obtaining a measure of an importance of a plurality of terms in the primary electronic documents; selecting one or more terms having a higher relative importance than other words as center terms and creating a group for each center term; calculating one or more group relation measure of one of the terms in the primary electronic document which is not a center term to the center term, each group relation measure specifying the similarity between the term which is not a center term and one or more terms of the group; selectively adding terms to one or more of the groups based on the one or more group relation measure; calculating a group score for a plurality of groups; and selecting, as key terms, terms from groups having a higher relative group score relative to other groups.