I used to love the Fighting Fantasy books by Ian Livingstone & Steve Jackson (two of the original Games Workshop crew, I think they my have been founders of the company ?)
I don't have an iPhone but I believe you can download the app from an iPhone store. I think you shake the phone to roll the dice which I think its quite a nifty little feature.
For anyone interested in a trip down memory lane to see the old book covers and summaries copy this link into your browser:-
PS. I presume you can no longer take sneak peeks at pages and now when you're dead you have to start over. Booo ! :)