This is great. I've always been amazed by the idea of free street parking in New York, especially in Manhattan, given the fact that a single space would be worth $1000 or more per month if it was part of an apartment, to say nothing of what decent storage space costs.
Michael Rakowitz has an interesting project, titled P(LOT), meant as a commentary on the use of public space for storing private vehicles.
Found via we make money not art. They have more information on their site. The artist's web site is not set up for easy bookmarking to an individual project. I first heard of Mr. Rakowitz at White Columns, when I saw documentation of his paraSITE project involving portable and temporary shelters for homeless people.