There's real momentum growing behind the idea of 'book-apps' on iPad, which go beyond the pure text of e-books sold on the iBooks store. Tactile interactivity was the hallmark of early book-apps like Alice and The Elements, but we're now into the second wave.

For example, Dracula: The Official Stoker Family Edition. It's just been released on the App Store, and offers nearly 300 pages of text and 600 illustrations to tell the classic vampire tale.

It comes with an original musical score and 21 songs from indie bands and singer/songwriters, as well as images, audio and film relating to the Dracula legend. As the name implies, the estate of author Bram Stoker is fully behind the idea.

Interactivity-wise, there's lots of cleverness going on: "From lighting up the words on a page with a lantern, unsealing the mysteries of letters and journal entries, blowing the leaves off of tombstones to reveal the writing beneath, and even using your own “blood” to reveal hidden text on a page..."

It's the work of a company called PadWorx Digital Media, which uses a game engine as the basis for its book-apps. Judging by the job it's done with Dracula, we'll be looking forward to upcoming titles using the same technology. Here's a video showing it in action: