Screen sharing is one reason I really like Google Hangouts on Air. A Google Hangout (GHO) is a video conferencing tool with some neat ways to integrate Google products and other add on's. A Google Hangout on Air kicks the GHO up a notch and broadcasts it live through YouTube.
Host video discussions with experts and peers using Google+ Hangouts (so much easier to use than video conferencing systems from years ago; connect with anyone, anywhere, anytime, at no cost)