I highly recommend
Multi-Platinum Pro Tools by Nathan Adam and Brady Barnett. It walks you through a pro-session, and includes a DVD with the walk-through video and session data. It covers a lot of stuff, to include using Autotune on vocals. It only came out a few months ago, but you should be able to find it Borders or Barnes and Noble for about $49.99 or so. Well worth it, in my opinion!! here's a link to it at Amazon:
http://www.amazon.com/Multi-Platinum...720748?ie=UTF8
Some other excellent books to have are Pro Tools Power! and Pro Tools Overdrive!(Ignite! is the beginners text, but you are probably past that stage if you read the manual!).
Of course, if you want to get certified, there's always Pro Tools 101 which is in stores(And I believe required for certification!).