In one of my earlier posts I blogged about Jing the screenshot and screencast software that allows you to capture your desktop. You can download the software for free at http://www.techsmith.com/download/jing/
Another instant screencast tool is Screenr. Unlike Jing, Screenr is a web-based screen recorder tool that captures anything you see on your computer screen or creates short 5 minute videos that you can share instantly. All you need is a Twitter account to get started. http://www.screenr.com/
A great tool for students to use to record demonstration tutorials on whatever they are doing on the computer. A perfect example is with the idea I suggested for SketchUp.