Icecast is a streaming media (audio/video) server which currently supports Ogg (Vorbis and Theora), Opus, WebM and MP3 streams.
It can be used to create an Internet radio station or a privately running jukebox and many things in between. It is very versatile in that new formats can be added relatively easily and supports open standards for communication and interaction.
Icecast is distributed under the GNU GPL, version 2.
I use Icecast only local, Traktor & mAirlist connect to it and send streams on the lowest possible bitrate, with the stream they both send Track & Title info and SAM Broadcaster is able to pick this up using a PAL Script.
My choice for Icecast is simply determined by the fact that Traktor does not support Shoutcast.
More info on the Icecast server and configuration options here