Bestparking.com is a cool parking rate calculation site.  It covers many major airports and the cities of Bostin, Chicago, LA, New York, Philly, San Francisco, and DC.

As somebody who regularly parks in NYC, and who is used to wondering if the price paid includes a tune up, a oil change and car wash, this is a nice site.  Once you select your city, your date, and your expected arrival and departure time, it shows you a Google enhanced map showing you the rates.  You can even reserve a spot at about half the parking facilities shown for no additional fee.

I have definitely not found a better way to do this.  In New York, you can pay $20 or $60 based on driving one block and hitting the right place at the right time.  This takes a lot of the guess work out of things.

Check it out HERE.