These are the functions to streaming

1) The Server

2) The Source Client

The Server

The server was running icecast - www.icecast.org which is an opensource  streaming multi-media application.

This was easy to setup actually- it has an xml file for config and you  just have to edit the options, i.e port folks will connect on, the  server-name/ip address, admin username and pass etc. Then icecast is accessible via the web, hence after installing creating an alias on apache or just a virtual-host to the icecast directory should easily get you going.

The Source Client

The next steps are to originate the stream and send it to the server. There are various opensource capture tools that can capture (from varios sources including mic), encode the source file, generate a stream and send the stream to the icecast server (in mp3 or ogg format). This url has a list of source clients you can use -

• http://www.icecast.org/ 3rdparty.php

We used Darkice, Muse and ices were the options we tried out. I think we used Darkice and Muse in some instances. We didnt have much success with
ices that i can remember - but it works as well.

In MacOS Nicecast works pretty well too. There are others too that you can give a try.