Parking spots as price controls

But not everywhere:

San Francisco is trying to shorten the hunt with an ambitious experiment that aims to make sure that there is always at least one empty parking spot available on every block that has meters. The program, which uses new technology and the law of supply and demand, raises the price of parking on the city's most crowded blocks and lowers it on its emptiest blocks. While the new prices are still being phased in — the most expensive spots have risen to $4.50 an hour, but could reach $6 — preliminary data suggests that the change may be having a positive effect in some areas.

There is much more here.