I am trying to build a web application that will stream an audio in the browser (without any plugins), with an ability to let other users join in to www.mys
You should take a look at binaryjs
From their description:
BinaryJS is a lightweight framework that utilizes websockets to send, stream, and pipe binary data bidirectionally between browser javascript and Node.js.
I've been thinking about WebRTC in similar use some time ago. It's one of solutions to create a WebRTC peer in server side node application. I've never done something like that, but check i.e. that question:
Use node.js as a WebRTC peer?