Kayak has Kayak Pro (iTunes Link) for the iPhone, iPod Touch, and iPad in the iTunes App Store for FREE (regularly 99-cents) for a limited time.

Kayak is the #1 mobile travel app. It includes flight and car search, hotel search and booking, flight tracker and My Trips, so you have your full itinerary at your fingertips.You can compare flight, hotel and car rental deals; book your hotel, right in the app. Just choose KAYAK as your booking option; track your flight status; view and manage your trip itinerary, look up baggage fees; access airline numbers and airport info; and airport terminal maps for over 100 airport.