Mixxx (PC and Mac) - a virtual mixer, lets you create advanced playlists and use a microphone. More & Download
B.U.T.T. - (PC and Mac) basic, lets you use a microphone or any other line-in source (a mixer, etc). More & Download
SHOUTcast DSP Plug-In (PC) - an addon to Winamp, lets you stream playlists from your Winamp Player and use other stream sources. More & Download
You may also use any other software compatible with SHOUTcast or Icecast servers, like premium (non-free) SAM Broadcaster Pro, Virtual DJ or RadioBoss
