Micro layouts are model train layouts that are small enough to fit into a pizza, shoe, or a match box. Most of these layouts include a circle of track and a few small buildings and some scenery, while others might run point to point. There are two sites that feature these types of layouts:
Carl's site started this venue or at least help make small and miniature layouts fashionable.
13th JAM convention report features many small and micro-sized layouts; some of these being quite whimsical.