An Audio CoDec and file format to replace MP3. OggVorbis's advantages are better compression and better audio quality and it isn't covered by patents like MP3 is. .ogg files support up to 256 channels, variable bit rate etc.
In 
a test conducted by the biggest German computer magazine (article is in German unfortunately) OggVorbis has also been proven to offer decidedly better quality at very low bitrates than any of the competing audio CoDecs. At high bitrates, MP3 and OggVorbis seem to be tit-for-tat.
Gettin used in the Real suite of tools thanks to the whole HelixCommunity thing.
10 pages link to OggVorbis:
