According to a recent O’Reilly Radar report, the fastest growing category on the iTunes App store is books. Some of these are full blown books at full cost. Others are $.99 or even free. This is an interesting potential source of being able to self-publish quickly on micro-topics. For example, a miniature 20 page book on how to do something very specific, sold on the App store for $.99 might be worth the cost to certain people. Like any other app, it might even take off and be uber-popular. On the same token, as an advertising ploy a free book might take off and garner a lot of attention. No…