The use of visual elements to enhance information seeking and discovery is a recurring research issue in the area of interactive information retrieval. Studies in interactive information seeking behavior have confirmed that the ability to browse an information space and observe similarities and dissimilarities between information objects is crucial for accidental encountering and the creative use of information [16,26]. Some kind of guided searching, enhanced by visualization techniques, therefore becomes more and more important to precisely discover information without knowing the right search terms. So far, this seems to remain the weakest point of interactive information systems [8,9,23].In the area of information systems, the use of information visualization techniques has been discussed since decades [2] Knowledge mapping, on the other hand, encompasses all attempts to use visualizations to gain insights into the structure and evolution of large-scale information spaces. Knowledge maps can take very different forms of visualizing the structure of information spaces, such as network visualizations, treemaps or geographic map like arrangements of knowledge structures [3,4,6,12,17,21,22]. As an activity performed in very different disciplines-and often independently from each other-it stands in line with the dominance of the visual in our culture [13]. Figure 1 shows an example of a map displaying the topical structure of a research field using a geographic metaphor [22].However, the established research domain information retrieval and the interdisciplinary domain of knowledge mapping have mainly been independent from each other. Both strands are driven by quite different epistemic perspectives. The use of information visualization in the area of information retrieval is predominantly focused on the support of information seeking activities by visualizations, whereas the knowledge mapping domain is motivated by the question of how knowledge structures and bodies of knowledge can be visualized best. Both domains have certainly the potential to 123