FGo! is a simple GUI front-end for FlightGear written in Python. It takes slightly different approach than any other such application - it combines a simple GUI which allows you to select a plane, airport, runway, park position and scenario. In addition there is text window where you can write more advanced command line options that will be passed to FlightGear.
In its current state it also provides a checkbox for terragear and supports different languages. FGo! is available for download from in the first post of its forums thread.
All one have to know to set it up and run it is in FGo!s README.