Mayberry over at Keep It Simple Survival has been talking about homesteading, and some other folks have been talking about living out of a motorhomes and motorcoaches. Incidentally, here's a page on how you can deal with floods while living out of a motorhome. See the article here.
My friends and I who are involved in tech, and construction have kicked around a ideas about using CONNEX Boxes for instant shelters, to jump start bomb shelter construction and also for sleeving abandoned mines.
In short, the idea for a bomb shelter or retreat is basically excavate an area large enough to pour a concrete pad capable of accommodating the number of boxes you want to link/stack together. All of your power/communications conduits would be run on the exterior of the boxes. The same for air exchange, water and waste pipes. A framework of rebar would be constructed over those pipes/conduits to surround the boxes. Then the entire thing would be encased in concrete, and then the area backfilled.
To sleeve an abandoned mine, you would need a horizontal mine opening. There are a number near where I live just west of the Sierra Nevada Gold Country. The entrance would need to be large enough to accommodate the CONNEX box, or be enlarged to do so. The box would be slid into the opening. Forms would be constructed at the front and rear of the CONNEX box and concrete pumped in to fill the void between the box and the rock wall of the mine.
We talked to a mining engineer about this idea, and he was somewhat dubious of the idea. He said that it would probably be okay in a hardrock situation, but he would actually have to survey the existing mine and its opening to determine how stable it would actually be. He said that calculating the forces that would actually be exerted on the sleeve was critical to determine if it was safe. He went on to say that this was definitely not an option in areas where the ground was soft like near coal mines. Then he warned about radioactive gasses like radon and potential methane accumulations around mines.
Here are some links to homes built from CONNEX Boxes:
Shipping Container Homes
And a blog from Afghanistan