We've lined up over 30 tools that let you do everything from finding more affordable tickets to predicting the best time to buy them, and even using a 3d map of your plane to select your seat.
Domestic
CheapAir.com - Searches for all regular and sale fares at the same time and allows you to filter the results on the fly via Ajax so there are no reloading delays.
Momondo.com - Offers search for nearly 500 airlines in nine languages.
Vayama.com - Uses an interactive map to help you choose your airports. Also generates 3D seat maps for your plane to help you choose your seat.
CheapFlights.com - Also operates CheapFlights.co.uk. In the US they assist you with finding cheap tickets via JetBlue, American Airlnes, Orbitz and Priceline amongst others.
CheapTickets.com - Offers up flights, car rentals, cruises and even train tickets.
Expedia.com - Besides being able to search all the major airlines, you can also book hotels, cruises and more.
Hotwire.com - Sells unsold inventory from major companies and offers them at a large discount by not showing you the name until after you book.
LessNo.com - Specializes in flights in the USA, the UK and Indochina.
Orbedia.com - A metasearch that allows you to check Orbits, Expedia, Travelocity, Hotwire, CheapTickets and more in one shot.
Orbitz.com - Books all forms of travel from airline flights to trains & cruises.
Priceline.com - Name your own price for airfare, hotels and car rentals, and then see what they return to you to meet your bid.
Trabber.com - Searches 30 websites for the cheapest tickets for users in the USA, Germany, Spain, France, Italy and the UK.
Travelocity.com - Probably as famous for their spokes-Gnome as their booking, they do go the extra mile giving you phone numbers to speak to an actual human if you need to.
Wego.com - Focuses heavily on international flights by searching numerous foreign carriers as well as domestics.
Yahoo Travel - Search all the major airlines with only low booking fees.
Non-USA
Airline-Network.co.uk - A UK-based search that focuses on long haul flights to overseas destinations.
Cleartrip.com - Flight and hotel booking inside of India.
DoHop.com - Part-owned by CheapFlights.co.uk, gives you the ability to search over 660 airlines worldwide.
FlightChecker from MoneySavingExpert.com - Focuses on budget airlines, offers charts to show you which part of the month is the cheapest time to fly.
Ixigo.com - Cheap airline search limited to flights inside of India.
Jetcost.co.uk - Jetcost searches multiple ticket sites such as Expedia, British Airways and more to help you find the cheapest prices.
Kayak.co.uk - Searches over 140 airlines and travel agencies and gives you the tools to book directly through them.
Liligo.com - Offers localized search of hundreds of airlines for Germany, Spain, France, Italy, Hungary and the UK.
Skyscanner.net - Leans towards broader searches for those with flexible travel dates. Also offers suggestions for those who just want to go somewhere, but can't think of anyplace themselves.
Miscellaneous
AirlineQuality.com - A site for rating airlines, their seats, airports and their premium lounges. Also offers chat rooms for people to discuss everything related to the airlines.
Farecast.Live.com - Microsoft powered service to search multiple sellers and predict for you if you should buy your ticket now or hold off for a possible price drop.
FlightArrivals.com - Check on flight arrivals, departures and reschedulings in the USA and Canada.
FlightAware.com - Track all of the flights in the United States in real-time. You can also narrow it down by carrier and see exactly where a flight is at any time.
FlightStats.com - Check the status of airports in regions all over the world, flights, rate the airports and discuss on the forums.
FlightView.com - Get real time updates on flights and the status of airports.
FlyMyCase.com - A shipping company specializing in picking up and delivering your luggage to and from just about anywhere in the world.