Sophie 1.0

I haven't tested this myself, but the tutorials look encouraging and I'm downloading it with a view to installing and using it to produce some multimedia online learning materials. It's free and seems targetting at academic usage, so it's the business from that point of view. Sophie 1.0 Available Now | Sophie: "Sophie is software for writing and reading rich media documents in a networked environment. Sophie’s goal is to open up the world of multimedia authoring to a wide range of people and institutions and in so doing to redefine the notion of a book or “academic paper” to include both rich media and mechanisms for reader feedback and conversation in dynamic margins." There are a bunch of tutorials here.