VLC Media Player – Cross-Platform Media Player and Streaming Server
http://www.videolan.org/

VLC media player is a highly portable multimedia player for various audio and video formats (MPEG-1, MPEG-2, MPEG-4, DivX, mp3, ogg, …) as well as DVDs, VCDs, and various streaming protocols. It can also be used as a server to stream in unicast or multicast in IPv4 or IPv6 on a high-bandwidth network. This has been added to World Wide Web Reference Subject Tracer™ Information Blog.