Hello,
I wrote some time ago a simple GUI front-end for FlightGear. It was written in Python and it takes slightly different approach than any other such application known to me - it combines a simple GUI which allows you to select a plane, airport, runway, park position or scenario with text window where you can write more advanced command line options that will be passed to FlightGear. I know, it sounds like crazy idea, but I have found it to be quite convenient solution (at least for me ).
Be aware that I'm a complete amateur when it comes to programming. That is why I can't guarantee this software will meet you expectations regarding usability or even run on your system. I tested it on Debian and got reports that it run on Ubuntu. Having said that I presenting it here in hope it will be useful for some of you anyway.
Regards,
Robert
UPDATE:
The software can now be downloaded at this address: http://sites.google.com/site/erobosprojects/flightgear/add-ons/fgo