Part of my Master's thesis was the development of a Finite-Volume solver for Poisson's equation for electrostatics on the Voronoi dual of a Delaunay mesh . I have been intrigued with the geometry of the Voronoi diagram ever since.
D3 has the ability to compute and operate on Voronoi Diagrams. My favorite example is the Voronoi Diagram with Force Directed Nodes .
While the mathematical properties of Voronoi diagrams are fascinating, I also find the layout intriguing from presentational and interactive points of view. I've adapted the above at source.html. A more experimental version is at voronoi_exp.html.