I'm sure this works, most likely, on other smart phones but I love the 
feature whereby you can be playing music, put it on pause wherever you wish, 
then go to your home page menu, or any other screen display, and tap the 
screen twice with two fingers, and the music starts and stops right there 
without having to go to the music screen.  I do this with the dramatized 
Bible called the Word of Promise.  I stop reading at the end of a chapter, 
and later, if for example, I am in my phone screen of contacts, or anywhere 
really, I tap the screen twice with two fingers and the Bible starts playing 
where I left off.  Tap it twice again at any time, any place, and it stops. 
If you go to your music screen, or your app screen where everything is 
listed, and open the Bible, a screen displays and tells you chapter and 
verse where you stopped.  Close the window and program, go back to anywhere 
else, tap twice with two fingers, and the Bible starts playing, or music, if 
you were listening to music instead.  I haven't done it but I'm sure it does 
the same with an iBook.  Pretty convenient.  Oh, by the way, I'm still using 
the iPhone 4S and have to wait a few months before I'm able to upgrade to 
iPhone five.

Phil.