As you probably know, online videos are extremely popular. Posting a video promo for you book on Youtube is a great way to generate some buzz about your book.
Many of the authors I work with are creating video "trailers" for their books and posting links to them on their websites and blogs, as well as forwarding them along with emails and news releases. With nothing but a little creativity and a home video camera you can create a fun and inexpensive marketing tool.
Each of these videos show a wide variety of approaches and personalities, but they are all great examples of how to use home video to create a great promo for your book. Not to mention that they look like they were fun to produce.