I can't take credit for finding this next tool (http://www.freetech4teachers.com/) but I'm sure glad that I found out about it. Join.me is a new collaborative web-based tool that lets you share your screen with people simply by telling them the randomly generated password. What you see in the image above is what you get. No user names or passwords, just click on share and you will be given a number. Share that number with the people you want to have access to your computer's image. Those people enter the number in the join box and away they go.
I will be using this tool in my classroom to share my screen with my students when showing them how to do something using the computer. You could also use this for professional development or have students share codes with each other and share their work from a world away. You can even chat with the people who are viewing your screen cast and ask them questions. How would you use this tool?