Here are my favorite air travel sites and tools and why.
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Seatguru
Find seat maps with leg room measurements, best/worse seats highlighted, power outlets, WiFi availability, and more. Search by airline or flight number. Crucial tool.
Flightaware
Track flights as they are in the air to see where they are. Works for flights originating in the US, UK, Canada and the Caribbean. If the flight originates from elsewhere, you can see it once it enters the US.
IFly
Fairly comprehensive guide to airports, with some notable gaps. The best place to start for layover ideas, terminal maps for plane changes, restaurant information, ground transportation and security checkpoint wait times at more than 400 airports.
Airfarewatchdog
Hands down the best airfare alert service. Powered by live people, including promo codes and accurate availability.
Gogo Inflight Internet is one of the leading providers of in-flight internet connection with service on some flights by AirTran, Alaska Airlines, American Airlines, Delta, US Airways and Virgin America. More in the works. But an unlimited pass ($39.95/month) or a 24 hour pass online ahead of time ($12.95), or, purchase flight passes inflight from $4.95-$12.95.