This type of functionality is already supported by on Windows, OS X, and, of course Linux-based systems through Chrome, Firefox, and even IE. I believe that the

This type of functionality is already supported by on Windows, OS X, and, of course Linux-based systems through Chrome, Firefox, and even IE. I believe that the first way to get this type of functionality was to use Mozilla's Prism project, which has been around since 2007 (though that is just the first that I am thinking of off the top of my head). I never end up finding these sorts of things to be very useful, since I always have a browser open anyway.