Aviation Safety Network.
Includes a list of all known hijackings since 1948.

Bumper Tracker.
Been bumped from a flight? This site not only gives you a place to complain, it includes list of airlines and results of their seating bumps. See how much compensation each airline is offering and pick up some tips on what to do if you are bumped.

Flight Arrivals and Departures.
Provides arrival, departure, delay and cancellation information for all commercial airline flights operating to, from, or within the United States. Search by airport, airline, or flight number.

Flight Explorer Fast Track.
Track any flight by airline, flight number, departure time, or airport. Includes maps of in-flight plane with exact location, flight path, and estimated time of arrival.

Flightaware.
Free flight tracker. Private (IFR) and commercial flight status, tracking, history, maps. Print terminal procedures, view airport and FBO information. Find current IFR routes for a flight, view weather maps and METARs.

FlyerTalk.
Tips and forums for the frequent flyer community.

SeatGuru.com.
A source for airplane seat information. Pick the airline you are flying, the type of plane, and see details about every seat on the plane -- which seats have the most leg room, the best view, a power port, a video monitor, storage areas, armrests, drafts, proximity to rest rooms, and more information critical to your in-flight comfort.