Swfdec is a library for rendering Flash animations and games. It was originally designed to be used for creating Flash plugins for GStreamer, but is a fully standalone library that only requires the Cairo library for drawing. It includes a GTK+ player (swfplay) and a Firefox plug-in.
Liboil is a library of simple functions that are optimized for various CPUs. These functions are generally loops which implement simple algorithms, such as converting an array of N integers to floating-poing numbers or multiplying and summing an array of N numbers. Clearly, such functions are candidates for significant optimization using various techniques, especially by using extended instructions provided by modern CPUs (Altivec, MMX, SSE, etc.).
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.
Schrödinger is an implementation of the Dirac video codec, a modern wavelet-based video codec. It features both an encoder and a decoder and GStreamer plugins. Mappings have also been developed for putting Dirac into both the Ogg container format and the MPEG Transport stream container format.