Most of us here in mobileread mostly read fiction ebooks. Multimedia makes sense for a lot of non-fiction (even if it is just basically like a bunch of monetised websites), but we haven't seen that done well in fiction form. I'm open to seeing where that goes, but I think it's a different market. The most "interactive" ebook I'm going for at the moment is a Choose Your Own Adventure book with hyperlinks
I'm posting a review of one soon and boy, I don't miss all that page-flippin'.