If you are traveling or living in one of 40 different US and 3 Canadian cities and you have a car then the BestParking.com app is a must have app. The app also has info for about 70 popular airports.
To see how this app works let me tell you of my most recent visit to San Francisco. I had an event on Pier 39 but I knew that the parking near Pier 39 is very expensive. So I brought up this application. I chose to look for parking for San Francisco. I was then give a choice of looking of a particular address, neighborhood, attraction or location. I chose to look for the North Beach neighborhood. I entered in the rough time for my arrival and departure.
Up comes a map marked with the cost of parking at a number of parking garages. The garage that I knew about which was right on the Embarcadero was $30, but only two blocks away I could park all day for only $10. This is a free app.