Considering that most schools might not have money for projectors in every classroom.
I think a some special presentation software is needed.
Software which make it possible to broadcast a presentation over the wireless connection. Such that the students can watch the slides on their own laptop.
It should also be possible to synchronize soundtracks with the presentation such that we get a combination of a podcast with a presentation. Such own can have a full lecture in on file which is smaller than a video of the lecture.
Presentation software could be useful for Show and tell slide-shows.