This paper is about support for the exchange of information and knowledge among researchers. We introduce the concepts of open archives and grey literature, which provide valuable sources for researchers who work alone. We analyse how users exchange information and knowledge and introduce communities to more adequately reflect the nature of human information and knowledge exchange. Finally, we present he functionality and implementation of the CYCLADES environment-a distributed and open collaborative virtual archive environment based on open archives, providing several services supporting individual researchers as well as communities of researchers.