Screen Leap. Screen Leap allows you to share your screen with anyone without registering or installing any special software.
Today, through Tekzilla I learned that Screen Leap offers a Chrome extension that can make screen sharing even easier. The extension allows you to share your screen from your Gmail account. When you have the extension installed you can share your screen just by clicking "share screen" in the dialogue box that appears in the lower-right corner of your Gmail screen. Check it out in the video below.
Applications for Education
Sometimes it is easier to show someone how to use a program on his or her computer than it is to write directions in an email. If you're the go-to tech help person in your school, Screen Leap could prove to be a handy little tool for you.