Shoutbox

I don't think this is possible, sorry. In conversationwindows (IM programs) you can only type, not make sounds (unless you send a specific command wich triggers a sound, the sound needs to be on both computers..yours and your contacts). If you want to let your contacts hear what you are playing, turn on voicechat and use a regular microphone (not a headset) so they can hear all surrounding sounds.