The Knowledge Exploration (KE) Technologies Laboratory is a web resource dedicated to the study of open source KE tools. KE tools allow users to interactively explore information resources and to discover explicit and implicit structures. KE tools typically consist of a knowledge repository: relational database, knowledge base, ontology or XML-based web service, tools for querying and structuring and interfaces for information visualisation and representation. As an example of a Knowledge Exploration Tool, an electronic version of Roget's Thesaurus has been compiled by members of the Knowledge Exploration Technologies Laboratory. Different interfaces have been developed using techniques from information visualisation and Formal Concept Analysis.