Tagging has become the most common way of annotating information and knowledge in a wide range of applications. The activity of tagging consists in creating an association between a resource (information) and another entity (a tag). However, simply tagging a resource does not allow to retrieve the context in which the tag was selected, leading to ambiguous annotations. Extreme tagging goes one step further by allowing users to explain the meaning of their annotations, and to tag the tags themselves. This provides additional meaningful ways of sorting and combining information about the tagged resources.
More: Vlad Tanasescu, Olga Streibel Extreme Tagging: Emergent Semantics through the Tagging of Tags International Workshop on Emergent Semantics and Ontology Evolution, ISWC2007, Busan, Korea, November 2007

Extreme Tagging Systems allow for tagging the tags and tagging relations between the tags.

Many thanks to the authors of this experiment: F.Badra, O.Streibel, V.Tanasescu, K.Wang, Y.Wang

Using the principle of Extreme Tagging Systems, we are developing a prototype of an Extreme Tagging System (eXTS) for a group of experts in a given field of expertise. Based on the idea of tagging concepts (tags) with associations (tags) as well as tagging the relations (tags) between the associations, we aim to automatically gather the description of expert knowledge in the chosen expert field.
Demo will be available soon!