Simple Audio Conversion with FFMpeg. Is that still a thing? I can’t keep up with all the forks.
On-demand System Tray. I can’t stand the Unity Panel. Give me back my WindowMaker. (Like that’s going to happen. Even MacOSX is disowning the awesome NeXT UX.)
How to add extra airplanes on FlightGear Flight Simulator. I’m not much of a gamer so I didn’t know there was such a game. But, judging from the screenshots, Linux games have sure improved.