PeerJS enables WebRTC browser-to-browser banter
PeerJS has a simple API allowing a peer connection to be made with three lines of code and takes care of WebRTC handshaking. To enable the clients to rendezvous, PeerJS is backed by PeerServer, a Node.js-based web server that is also open source, as well as being available through a free cloud service, PeerServer Cloud, after applying for an API key.
PeerJS is a work-in-progress though and, as of the most recent status update, is reliant on the implementation of WebRTC DataChannel and other features on the various browsers. Currently, only Chrome 26+ (Dev and Canary channel versions), but no Firefox versions, can make use of PeerJS. The developers of PeerJS say they do expect DataChannel to be in stable versions of Firefox and Chrome "in something like 2-3 months".