Naiocast is a free Web based streaming media server, similar to SHOUTcast and Icecast. It currently supports MP3 audio streams only. It can be used to create an Internet Radio station or a privately running jukebox.
It requires neither expensive dedicated servers nor compilation on the target machine.

Naiocast, the project, includes:

Naiocast Server - It is capable of streaming MP3 content over the protocol used by SHOUTcast (sort of HTTP). It works on a normal web hosting (Linux). Apache is recommended as the most robust and full-featured server for running a Naiocast Server.

naioSC - a "source/sender client". It sends stream audio to a Naiocast Server to broadcast to clients. It runs tipically in the place where the audio is generated (e.g., a studio, your computer).

All you get is just 3 (CGI) Perl scripts: a sender (local), a receiver (remote), and a player (remote).

Broadcasting from one own computer would appeal to many casual users were they not to immediately encouter a Firewall/Router problem.

Broadcasting is almost always blocked until adjustments are made to the Firewall or the Router, causing many people to lose interest after they discover they have to deal with such a technical obstacle.

Naiocast lets you set up your Radio even if your network is behind many different Routers or Proxies.

Also, Naiocast allows you to transmit and listen in that network environment, typical in businesses, that use a Firewall to disable everything except web traffic, so no streaming is possible.
That is accomplished by using HTTP POST Method. It is kinda endless upload from your computer to a web server. As you probably know, you CAN upload stuff from your computer to a web server, although your computer is behind many different Routers or Proxies. That is because outbound port 80 (HTTP) is not blocked by default.
naioSC sends the stream from your computer to a Naiocast Server on the internet. Users connect to the Naiocast Server (not to your computer!) to listen to your stream. Thus, your IP address is not revealed.

Naiocast is an open source project written in Perl and released under the GNU General Public License.

You can get more on all of this at: http://www.theartofweb.net/txt/naiocast.html