Together with Moritz Stefaner (www.der-mo.net) we developed in the WINDS project a visualization for heterogenous neetworks. (see der-mo for a demo). This radial browser was designed to display complex concept network structures in a snappy and intuitive manner.
Click the center node for detail information or click adjacent nodes to put them in the center. The arrows on the top left can be used to navigate your click history. Use the dropdown in the upper right to directly access nodes by name. The varying distance to the center node for nodes with many neighbors was only introduced to enhance legibility and does not have a special semantics.