FlightGear- the home of FlightGear, and the place to download the main program, additional scenery and a huge selection of aircraft
FlightGear forums - a great source of information, help, and entertainment
FlightGear wiki - a very informative resource, recommended reading for new users

Helijah's Hanger - a huge selection of high quality aircraft
UnitedFreeWorld - site with many liveries, models and scenery add-ons
Dave's Hanger - home of some of FlightGear's best aircraft, including the F-4 Phantom II series
GR-TUX's Hanger - home to many high quality aircraft
Detlef Faber's Hanger - home of several vintage combat aircraft
Gij's Hanger - selection of Netherlands related aircraft and scenery add-ons
Hoerbird's Hanger - home of several aircraft including helicopters, jets and gliders
Buckaroo's Hanger - home of a few quality aircraft
Anders' Hanger - the best lighter-than-air aircraft available for FlightGear
Tat's Hanger - a good selection of mostly Japanese aircraft
Stewart's Hanger - home to several fantasy aircraft
MDSmith's Hanger - a small but growing collection of aircraft
FlightGearLivaries - home of many liveries for all sorts of aircraft
N-SCOT's Hanger - source of VX squadron liveries