[einhverfr]

One useful thing would be an excise tax for land rentals. This would drive up the cost of renting (but probably not the price, since rentals are competing with purchases) in comparison to owning in terms of both one's own home and productive property (farmland, office space, etc). This means less incentive to be a landlord. Ideally the home should be productive property but all too often it isn't.

[eli_gottlieb]

This is exactly the conclusion Henry George came to when he investigated these phenomena: a land-value tax. I, personally, would couple it with a rebate/"prebate" for a certain value, as society's way of saying, "If you use less than $X in land/commons value per year, that's fine." The X would be set so that the fat middle of the bell curve of single-family residences would fall within X.