The site is spotscout. I read the "how it works" section not because I am looking for parking spaces (I am not using a car here in NYC) but because I am interested in parking innovations. The site allows you to register and then reserve a space, either on your PC or on your mobile device (a bit problematic when you consider many people might be doing this while driving). These spaces would typically be in a private garage or someone's driveway. The site shows you the distance from your destination in walking time, the type space, and other features of the spot, as well as the price. Thus if you need a space for 2:15 pm today, you can reserve it now.
The part that's a bit iffy is the "selling" of on-street spaces. These are public spaces and are therefore available to whoever gets there first. But a person who has secured one may "sell" his or her leaving time, so another car can be lined up, ready to take it. Just say no to this one. There are too many variables. The arriving car may get there early (probably would want to) and may be holding up traffic, waiting for the departing car to depart. Another car may get there first, one who is not signed up with spotscout. It's problematic. But the other part, the reservation of off-street spaces, this I like. It makes maximum use of available spaces, and offers them at the going rate. When you consider there are, as a conservative estimate, seven spaces for every vehicle in the US, you can see that what we need is not more spaces but better management of those we have, and prices that match the value. So I say yeah! to this part of the program.