PLIB is a set of libraries to write games and other realtime interactive applications that are 100% portable across a wide range of hardware and operating systems. It's used by Majik3D, FlightGear, and others, and includes libraries for GUI widgets, sound replay, geometry, scene graph, joystick, and fonts/text.
Elisa Media Center is a project to create a media center solution for GNU/Linux and Unix operating systems. Elisa runs on top of the GStreamer multimedia framework. In addition to personal video recorder functionality (PVR) and Music Jukebox support, Elisa also interoperates with devices following the DLNA standard, like Intel's ViiV systems.