Do you need to generate a map for a city and do it quickly? A strong recommendation is Oskar Stalbery’s City Generator.
You simply click on the grid to start and the city grows before you. Click again and the city grows again, pick the square you want to add more detail too. As a rule the more often you click on any square the more dense and complex the roads in that area become.
This city generator is elegant and suitable for fantasy and contemporary RPGs. There’s a mix of city grids (like US cities) and curvy organic growth (like European cities) and the result, I think, is a good compromise.
An alternative to look at is this Fantasy city map generator.