PresentationIO is a free web application that allows you to share your presentation with others in real time and on any device. Upload your presentation to presentation.io and  press one button to get started. You control the presentation, colleagues and partners near or far follow sync’ed on their own device. This means everyone you’re presenting to will have your presentation displayed on their very own screen. You can make your presentations interactive by using the discussion pane during or after the presentation.

How would you use this in education? I can see the benefits for secondary teachers and administration staff. The free version does limit the number of presentations that you can upload and presentations do expire after 4 hours.

Source: Claire Collier