Today the Web serves as the central information hub for almost all areas of daily life, where issuing a simple keyword query offers access to a dazzling array of information. And this does not only cover trivial information, also in the area of professional or scientific information there
is a clear trend towards easily accessible information provisioning via the Web, e.g. in digital
libraries, open access journals, or topically focused forums or newsgroups. But here, querying
mostly is much more complex and offers a vast variety of community-specific interfaces, specific
indexing schemes, and metadata-based access. This increased complexity leads to the question
whether such effort is really needed or if general purpose knowledge portals, like for instance Wikipedia, would already be sufficient even for sophisticated tasks with a clear thematic focus. In this paper we explore the challenges and chances of specialized thematic digital libraries reviewing typical use cases from different disciplines like chemistry or mathematics and argue that although one size does not fit all, there is a lot to learn from general purpose portals.