If you want to run your own radio station, and have the bandwidth to send out the audio, Shoutcast is a free solution that can get the job done.

Shoutcast currently only works with MP3 files and only sends out one stream per server. If you need a more robust solution, Icecast server software supports multiple streams and OGG format.

On the up side, shoutcast.com is a very popular website and by listing your radio station on their site, you could get all sorts of new traffic from all over the world for your new station.

Shoutcast needs two components to run. First you need the main Shoutcast server, which sends your music out to the world. Next you need the Shoutcast DSP plug-in, which "feeds" music from your server's hard drive into the Shoutcast server so it has something to broadcast. Instead of feeding MP3 files, you could also send live audio or other audio sources to the Shoutcast server. Both of these software packages are at Shoutcast.com.

If you want, you can also feed your Shoutcast signal to a third party radio station like Live365.com - but they usually charge you for this service and the fees can get quite hefty. They also interject their own ads into your audio stream.

Shoutcast Website