Social Semantic Web subsumes developments in which social interactions on the Web lead to the creation of explicit and semantically rich knowledge representations. The Social Semantic Web can be seen as a Web of collective knowledge systems, which are able to provide useful information based on human contributions and which get better as more people participate. The Social Semantic Web combines technologies, strategies and methodologies from the Semantic Web, social software and the Web 2.0.
DBpedia is a community effort to extract structured information from Wikipedia and to make this information available on the Web. DBpedia allows you to ask sophisticated queries against Wikipedia and to link other datasets on the Web to Wikipedia data.
SIOC provides methods for interconnecting discussion methods such as blogs, forums and mailing lists to each other. It consists of the SIOC ontology, an open-standard machine readable format for expressing the information contained both explicitly and implicitly in internet discussion methods, of SIOC metadata producers for a number of popular blogging platforms and content management systems, and of storage and browsing / searching systems for leveraging this SIOC data.
OPO provides a way to describe the data relative to user's presence in online social systems, for the purposes of data integration and exchange among heterogeneous systems. The presence information, scattered and distributed all over the Web can be consolidated using OPO-based tools.
Stumpedia is a social project and community effort that relies on human participation and folksonomies to index, organize, and review the world wide web. The aim is to help build Natural Language Processing and the Semantic Web.
Semandeks is a bottom-up approach for building the semantic web. Its strength is the UI it uses.
Twine combines features of forums, wikis, online databases and newsgroups and employs intelligent software to automatically mine and store data relationships expressed using RDF statements.
Faviki and Tagnauts are social bookmarking communities which restrict their users to tags to which Wikipedia articles exist.