Curbed recently featured the micro 3D printed Ittyblox buildings on the web-based collective called Shapeways. Produced at a 1:1000 scale, you can collect and build you're own cities, complete with LED light effects for nighttime enjoyment. Of course, the mini model of the Guggenheim released to celebrate the New York MakerFaire is by far my favorite. More here and here.
Image via shapeways.com