Streaming live content with linux servers?

I am going to be setting up a server for streaming live audio content. What
are some ways to go about doing this and if possible, what are some good
online sources of information? If I cant find a Linux solution I will have
to setup a NT box, which I don't want to do. Were most likely gonna use
Real Audio, but Id like to see what else is out there before I make a
decision.

Thanks,
John Albee