Barrie Lovell has created a wonderful temporary layout system with small scenery plates to allow rapid setups of different layouts at his whims!
Richard Bell has made a robust mini tram layout in a space of 28" x 18" using the tomix mini curve track. He has packed a lot scenery into a very small space along with wire catenary.
Nick Yee has found the solution to a layout in a small space by using Bandai B-Train Shorties.