Surely I'm not the only one here who thinks book trailers are awful. They make would could be a AAA novel seem like a tie-in for a made-for-TV movie. But I've recently discovered a better way to promote your story. I don't really have a name for it, maybe video book, so let me just describe it and then show it to you.
I was playing
Lost Odyssey, a fantasy role playing video game. The main character, Kaim, is an immortal mercenary who is 1,000 years old. After an accident, he is unable to remember his past. As the story progresses, bits and pieces of Kaim's memory return.
His returning memories are presented via short stories written by Japanese novelist Kiyoshi Shigematsu. For example, in one scene Kaim sees a church bell and it triggers a memory. The memory is a short story that you (the player) actually read on screen. It consists of a periodically changing background image with the text displayed Powerpoint slideshow fashion, with sound effects at appropriate times. Might sound confusing so, I'll just show you one of the short stories.
http://www.youtube.com/watch?v=SHGEANWBYVA
In my opinion, this is a much better way to present a story than a book trailer. However, you might be thinking, that's great for a short story, but what about a novel?
While you could present an entire novel this way, I think it's best for suited for short stories. However, you could present your first chapter or a random excerpt in place of a book trailer.
This format could also be used to make online journals more interesting.