The following sites provide music in the Ogg Vorbis format:

Magnatune: [1]

A music label that sells music in the Ogg Vorbis to end-users as well as provides commercial licenses for use in various projects.  With the slogan of "we are not evil," Magnatune promises to never use any form of DRM [2].

The Kahvi Collective: [3] 

Provides a variety of music in the Ogg Vorbis format available under a Creative Commons non-commercial license.

theGREENzebra's Music Page: [4]

A variety of music and video game theme songs provided in the Ogg Vorbis format.  No license information is provided at this time.

The Music Project Fabco: [5]

Fabco is a music project based in Austin, Texas.  They distribute most of their music in the Ogg Vorbis format, under a Creative Commons non-commercial license.

Hörstreich: [6]

Hörstreich is a punk rock band from Germany that distributes their music in Ogg Vorbis format under a Creative Commons non-commercial license.

URN Student Radio for Nottingham [7]:

UK based student radio that broadcasts a variety of content, available in Ogg Vorbis format.

WCPE -- The Classical Station: [8]

Streams classical music over the internet in Ogg Vorbis format.

Zentriert ins Antlitz: [9]

A german band that provides their music for download exclusively in the Ogg Vorbis format.

DuskTilDawn: [10]

A dutch band that provides their music for download in the Ogg Vorbis format.

Cauterized: [11]

A danish band that provides their music for download in Ogg Vorbis format.

Special thanks to the Xiph Open Source Community at Vorbis.com [12]:  Many of the links listed on this page were discovered on their page: http://www.vorbis.com/music_links/ [13]