"A collective identity refers to individuals' sense of belonging to a group.
Identity is a tough issue on the Web. Normally, a web user may have varied identities on different sites. These varied identities, however, cause serious problems when people try to organize their information of interest across the boundaries of web sites. To address this problem, web researchers have issued the project Open ID that allows users to use a single ID over the entire Web.
But OpenID, even if it would be a standard over the Web, is not the end of the Web identity issue. Similar to that individual persons have their particular roles in real life, individual identities on the Web must gain their particular social roles in virtual life. The identification of these roles is particularly important when we would start to manipulate human generated information on the Web, i.e. collective intelligence, collective behaviors, etc. Only until humans or machines may identify the social roles of the information producers or owners, these humans or machines may be able to properly manipulate the information. The research of collective identity will focus on the identification of social roles of individual identities.
The collective identities are identities of identities." (http://yihongs-research.blogspot.com/2007/12/collectivism-on-web.html)