Get comfortable with iTunes 10, Apple’s popular music-and-media organizer and player. Don’t just read about it: See it and hear it with step-by-step video tutorials and valuable audio sidebars delivered through the Free Web Edition that comes … see full wiki
Just a few years ago, a book like Using itunes would have been laughable. After all, itunes was just for downloading music. Since the advent of the iphone, ipod, ipad, etc though, itunes has become a whole lot more than just music. More and more, it's becoming a department store of media options and a book like Using itunes is invaluable in helping us understand our options.
Essentially, any download you need for your iphone(music, ringtones, movies, ebooks, etc), itunes can help. That's probably pretty obvious to most iphone users. What's interesting though is that itunes is now looking to make things easier for the user, both on their pc and their mobile devices: organizing, syncing, reducing clutter, creating playlist, multiple media options. Thus, opening up possibilities for a wider range of users.
Using itunes provides a good description of the various features complete with step by step instructions. There are also lots of pictures and videos that you can watch online. Suitable for those new to itunes but equally valuable to those who haven't used itunes in a while.