D3: www.d3js.org
Voronoi Example: http://mbostock.github.com/d3/ex/voronoi.html
Updating on the example above, this library uses d3 to animate and draw successive iterations of Lloyd's algorithm. This produces a nice visualization of a random Voronoi tesselation becoming a centroidal Voronoi tessalation.
Features: -Vary number of regions -Lloyd's method iteration animation -3 boundary region behaviors - repel (normal), attract (push), and hold fixed (pin). -Delaunay triangulation (d3 handles this now) -Non-constant density (using various methods for integral approximation)
Future: -Mouse selecting points to hold fixed -Mouse splitting of regions into more voronoi regions