Actually that's not all you can contribute. There's also documentation, with the FlightGear Manual... and this wiki of course! To contribute to the wiki, head off to the Wiki Portal. There's a lot to do there too.
If you want to get in touch with other developers, register an account at the forum, and for core development subscribe to the mailing list too and consider visiting the Bug tracker.
See request for comments for a list of long-standing issues and challenges affecting FlightGear's evolution and overall development progress (admittedly a little outdated meanwhile). Also see the Jenkins build page and the Bug tracker.
