The World Wide Web (WWW) can be seen as an ideal platform for enhancing argumentative expression and communication, due to its ubiquity and openness. Much argumentation takes place on personal blogs and on unstructured or semi-structured discussion forums. Recently, an increasing number of Web 2.0 applications provide specific support for large-scale socially-contributed argumentative content. When compared with traditional methods of Web discourse, these tools enable better visualisation, navigation and analysis of the `state of the debate' by participants and, potentially, by automated tools. In this paper, I outline some potential benefits of Semantic Web techniques in supporting mass-scale, socially-contributed argument tagging. I also present some recent research in this direction. Key words: Argumentation, Web 2.0, Semantic Web