PeerCast is a simple, free way to listen to radio and watch video on the Internet. It uses P2P technology to let anyone become a broadcaster without the costs of traditional streaming. This means you get to hear and watch stations not normally found on commercially funded sites.

Features :
Support for MP3, OGG Theora and Vorbis, WMA, WMV and NSV.
HTML (Linux/Windows) and Windows task-bar icon interface
Remote configuration via any web browser
Extremely low memory footprint and CPU load
One click streaming - click on any peercast:// URL to start listeningâ? 
Direct streaming - PeerCast can act as a standard streaming server such as Shoutcast/Icecast to provide both direct and P2P streaming.
Multiple broadcasting - use mount points to broadcast multiple channels from the same server
Anonymous broadcasting - clients do not tell each other if they are the source or just listening
Remote broadcasting - broadcast to a client located on another machine anywhere on the Internet
Icecast/Icecast2/SHOUTcast/WindowMedia streaming support including relaying from external sources.
Support for all popular media players, WinAmp, XMMS etc..
Fully decentralized - any PeerCast client can be used to setup a private relay or provide connection bases to the main network
Security settings to control access rights for Connections/Broadcasting/Admin etc..
IP address filtering and banning
Custom settings to limit bandwidth and the number of connections in/out
Does not require incoming ports to be configured
Full support for ICY-Metadata (MP3) and OGG Vorbis comment headers for title/artist/song display
One-click play for any channel straight from the Taskbar icon
Favorite channels list allowing almost instant reconnection to your channels
Freeware, not ad/spy ware
Open source
Now includes OggCap - Video broadcasting tool.