A perfect example of urban infill, courtesy of the Wall Street Journal:
In Tokyo, where every sliver of land is at a premium, a few feet of unused private property near the front entrance of an apartment building can be used to sell muffins. A patch of storefront space transforms into an ad hoc vegetable stand for a farmer or a consulting space for a fortune-teller.
This is the exact approach that metropolitan areas need to take, and a great boon to small entrepreneurs and other makers. It certainly cuts through the red tape of zoning laws and the like.
Even in the urban context, these microrentals are not an instance of packing in more people like sardines (whether this would work outside of the hypercrowded Tokyo is up for debate), but rather matching supplies of valuable land with those who need it. Just for a little while.