Diaspora: A Free Battlestar Galactica Fighter Sim

After four years in development, this little gem is released.  You get to fly in a Viper, blow up Cylons, and escort your battlestar and it looks and plays beautifully.  It is built on the FreeSpace Open engine, a community-developed extension of FreeSpace 2's engine, so it is fully moddable and includes a mission designer for your own missions and campaigns plus all the necessary debug tools.  It runs on Mac and Linux, too, so you have no excuse to ignore it.