Windows/Mac: Join.me is a free tool from the creators of LogMeIn. Download the app, run it, share the URL with a friend, and you’ve got nearly instant screen sharing with text chat, voice conferencing, mouse sharing, and more.
Visit Join.me, click the share button to grab a copy of the software, run the software, and share the link. Your friends or coworkers visit the link and they’re instantly connected through their web browser into the sharing session. There they can chat with you, share your mouse (if you allow it), call into a free conference call number so you can all voice chat while watching the demonstration on the shared screen, and even share files with each other.