LiveSlides is a powerpoint or keynote add-in that enables embedding live content to your slideshow presentations. It works by adding browser capabilities to your presentation software without the look of a browser. Embed content such as web videos, calendars, maps, twitter feeds, polls, quizzes, and others, and present them as live content, activating features such as audience participation and collaboration. (Note: to make use of its features, you must have an active internet connection during the presentation.) Free.