[Unfortunately no longer valid link] Spark developers. utilities in development are available here for testing. There are some handy programs like Lattice for creating internal frameworks for printing.
The Microscape is a really cool art-mural of a city. You can purchase a printed ‘square plot of the city’ to give your mantelpiece a cool, kitschy touch, or go ahead and purchase adjacent plots to make a crazy mural of your metropolitan city.