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The term community is not specific enough and it is not clear to me whether it refers to a subject, academic departments, etc.
Communities and Collections Structure
Although it is not directly related to usability of DSpace, I think people working on repositories will find it useful when they face the task of building an structure of Communities and collections for their repository.
Our repository's communities and collections are more or less structured in the way of thinking of the librarians and the way the university is structured. For example, we have a top level community "Research" broken into departments and finally on the type of document.