I have written a Google gadget(link) as a demo of Delaunay triangulations and Voronoi diagrams. This gadget doesn’t support IE. If you are using IE, please go to this blog(though in Chinese, you don’t need to read any Chinese character).
I extend those codes to contain Voronoi diagram. It is written as a Google gadget so it can be added into some Google services, like Gmail or iGoogle.