Elisa Media Center
Elisa is easily described as GPL‘ed Media Center (ala Front Row) for Linux. It is developed using Python and uses the open source gstreamer framework, which is already the default in most Linux distros including Ubuntu. The development of Elisa is initiated by Fluendo, the company that provides the proprietary MP3 plug-in for free.
From the FAQ, Elisa is supposed to be able to view photos, stream web radios, watch videos (and DVDs), play music, even act as a PVR! Sounds very much promising.
Here is a guide from their Wiki to run Elisa on Ubuntu Dapper. I haven’t tried this, since it includes checking out unstable code. Just being save here. :D Meanwhile let’s just droll over the screenshots and video screencasts.