I just got a promo code valid for $5 Off Airport Parking at several off-airport lots at most major airports in the USA. The additional standard $5 booking fee is also currently being waived so it's more like $10 off. This code works GREAT to cut parking costs for cheap lots and especially for shorter rentals. If you use off-airport parking, this should help you get a nice discount.

To book, go to: www.aboutairportparking.com

And enter promo code: TravelDec09

This deal is for parking reservations made between 12/1/09-12/15/09, although the reservation can be made for any date in the future, in fact I was able to book some dummy reservations years in the future using this code. Reservations can be cancelled up to 24 hours in advance with no penalty. So if you know of your travel plans in the future, now is a good time to book parking with this code to save some coin.

In just checking 2 airports that I might use for parking, and as an example I was able to find:

1) PHX: $2 parking for one-day.
2) OAK: $4.76 parking per day on a 4 day reservation

Those are the only two airports I checked, so I'm sure there are plenty of great deals out there at other airports as well. From what I saw, their website was very functional as it allows you to comparison price vs the official airport parking lots as well as other local parking lots. And there's also a useful mapping function of all the lots available as well as user reviews of each lot. Enjoy. ^^^^^