The humble browser. Its main purpose, for many years, was to serve up simple HTML documents and provide information on just about any subject you could think of. In the last decade, with broadband taking over from dial-up, and net connections getting ever quicker, websites have increasingly provided applications usually restricted to the desktop.
With the evolution of languages such as HTML, CSS and JavaScript helping push the limits of what could be done, we find in turn it provides new opportunities in openness and sharing.