Office Mix is a free add-in for PowerPoint that's designed for educators. With Office Mix you can add audio narrations to your PowerPoint presentations, include a screen cam video of yourself talking (if you want), draw on the screen as you talk, insert quiz questions for students to answer, and publish to the "cloud" for easy linking from Sakai. You can also see detailed data on what each student viewed and for how long, as well as each student's answers to any questions you inserted.