streamTranscoder takes the output from
SHOUTcast/Icecast/Peercast/KasterBlaster servers or a sound card input and
transcodes them to another SHOUTcast, Icecast, or Peercast server in MP3 or
Ogg Vorbis format. It can transcode the input audio by resampling or
re-encoding, as well as changing the format from MP3 to Ogg Vorbis (or vice
versa).

WWW: http://bsdforge.com/projects/audio/streamTranscoder/