I wrote a lot of code to clean up the Voronoi output. Something that finds the size of a polygon/block and if its smaller than some limit merge it with a neighbouring block. Heres an output of the block map (finally some real results) the cool thing is you can just keep hitting a key and it generates another. I'm supprised how good the voronoi it looks without any tinkering, I was expecting to have to do a lot to make streets look like streets etc...

Every five attempts at running it crashes with a mysterious 'zero length edge' message while shrinking the blocks, I'm about to go and look into it....