I'm just getting started with this tooo.
Try vlc, it is a product from VideoLan (gpl.. all that good stuff).
If you have darwin, you should be able to compile it, if they don't have a bin for mac.
I run debian, and I compiled it so it would work better.
I'm still testing it, sooo all I can say is that it fires up, looks good, and I can pull up a wav file and play it (using mplayer) from my web page.
It's hard to test these things when you only have 2 computers.
Plus, like I said, I'm new to this.
I am building a custom debian distro (for nerds to start out with) and I want to have complete multimedia abilities WORKING, not just installed.... hence this is why I'm messin with streaming now.
Like I said, I 'think' it is working.. (there is NOTHING more frustrating, than trying to fix something that IS working-- because you don't know it's working!! ) :]