Air

OAG - The Official Airline Guide - Independent provider of travel information products and services, offering business travelers, corporations and the global travel industry information to make effective travel planning decisions.
http://www.oag.com/

Airwise - News and information source for airlines, airports and air travel. Also includes discussion boards.
http://www.airwise.com/

AirlinesAndAirportLinks.com - Database of links to airlines and airports around the world.
http://www.airlineandairportlinks.com/

ITA Software - Plan air travel with an advanced shopping tool displaying a summary of all flight travel options. Cannot purchase tickets online at this time. North America flights only.
http://www.itasoftware.com/

Instone Air Services - A specialist in the air transport of animals worldwide.
http://www.instoneusa.com

Bel Air Travel - Offers Canadian low-fare flight reservations.
http://www.belairtravel.ca

IAPA - International Airline Passengers Association - Offers hotel discounts, car rental savings, flight reservations, travel insurance, airport VIP lounge access, airline safety representation and luggage protection.
http://www.iapa.com

The Budget Traveller's Guide to Sleeping in Airports - Reviews including the best and worst around the world. Tips for sleeping comfortably and safely while grounded, articles, news and other strange places to sleep.
http://www.sleepinginairports.net/

FlightArrivals.com - Independent arrival, departure, delay and cancellation information for all commercial flights across the U.S. and Canada.
http://www.flightarrivals.com

HowStuffWorks: How Airport Security Works - Illustrated tour of the current technology used in airport security.
http://www.howstuffworks.com/airport-security.htm