Introversion City Generator
I picked up the humble introversion bundle several days ago. If you've not heard of it, the humble bundles are basically game bundles where you choose what you wish to pay and how it is split between developers, charity, etc.
Anyway, with the latest one came two tech demos, one of which is a modern city generator. It's very much a demo but it does generate a rather nice city. It has only basic settings to choose from (small, medium, large, omghuge, and whether you want it in shiny polygons or wireframes). There's also no export feature so you have to printscreen or the like.
It does use a seedcode thing though so if you use the same seed as before, it will generate the same city.
I have attached an example of the output below.
I would love to see them develop it a bit more so you could do more things with it. But it's still pretty fun to play with as is.