A Vook, as you may have already heard, is a video book. To take it a bit further and quote the full Wikipedia definition, "A Vook is a digital book type that combines video, links to the internet and text into one application that's available both on the Web and as a mobile application."
The company behind the Vook, named Vook.com, was officially launched on October 1, 2009 and currently has about three dozen titles available on the iPad and iPhone platforms. These range in price from free to over $15, with content ranging from public domain works to Deepak Chopra to Anne Rice, but the majority are priced between $4.99 and $6.99.
If you are not sure about how well you will cotton to this "Read It! Watch It!" concept, you might want to try a free vook first, like this presentation of 10 of Shakespeare's love sonnets: