E-mail-based conversations between thousands of people-very large-scale conversations (VLSCs)-now take place in a variety of on-line public spaces such as Usenet newsgroups and large listservs. This article describes the author's prototype Conversation Map system, which can automatically analyze and graphically summarize thousands of e-mail messages exchanged in VLSCs. Example conversation maps of nine VLSCs are presented. Finally, the sociolinguistic analysis performed by the Conversation Map is discussed as a form of artificial dialectics, and the graphical summaries produced by the system are considered as potential common ground between participants in a VLSC.