This is a simple WebSockets app which demostrates how an event could be sent from one browser to another device's browser.
The code was adapted from Martyn Loughran's em-websocket tutorial article http://rubylearning.com/blog/2010/10/01/an-introduction-to-eventmachine-and-how-to-avoid-callback-spaghetti/ which was published as a Gist https://gist.github.com/mloughran/604404
The idea would be to eventually make it into a snippet which could be launched from a browser bookmarklet to add synchronisation between browsers on all kinds of devices.