Business, Transportation and Logistics, Aviation

AeroTransport Data Bank

Provides information on all airlines and transport aircraft operators, worldwide, with history on more than 150,000 aircraft and 8,000 airports

http://www.aerotransport.org/
FlightStats

Real-time flight status and historical flight delay information.

http://www.flightstats.com/
Professional Pilots Rumor Network

Discussion forum covering most aspects of aviation.

http://www.pprune.com/