The Planning Department of the City of Amsterdam has created a number of interesting Google Maps, all of which can be found at maps.Amsterdam.nl. They have now also created the Amsterdam 'Map of Maps', a mega-map of Amsterdam, which allows you to view all the mapped city data on one Google Map.
The map includes a large number of data layers, including property value, soil quality, vacant offices. Dutch lovers of maps should also check out CitySDK and the interactive BAG Viewer. Both of these maps show the age of nearly 10 million buildings in the Netherlands and are great mapped visualizations of very large data. The two maps are great tools for exploring different patterns of urban development in Dutch towns and cities.