Steve Jackson's Sorcery! is an old series back from the early 1980s where you "played" through a sort of Choose Your Own Adventure-style story, except that instead of just flipping pages, you actually cast spells, fight in combat and do other fantasy-based activities. These books were reprinted back in 2002, but it's been announced that they're coming to iOS soon, as fully interactive books to play with.
Most interactive books on the App Store are either meant for children or show off only a limited amount of interactivity, but these seem different -- they're heavily dependent on text, but they do offer some nice interactive touches from the original books. There's even some fun procedural stuff: When you do combat in the game, the book creates custom-made text for you to read about the outcome of the battle.
It all looks very cool, and it's a nice throwback for those of us who played with these books all those years ago. Steve Jackson's Sorcery! is set to be submitted to the App Store right away, so we should see it for ourselves very soon.