Free Guitar exercise Book
At amazon you can download this e-book (kindle version) for free untill 20.07.2013
I have not checked the book yet but i will and maybe its interesting for some of you, too.
By the way, who has not a kindle yet (like me) can download a free pc kindle app from amazon.
If this works for every amazon account or just amazon germany (easy to register, isnt it?) you also have to check yourself (i checked it with amazon.com and it seems to work).
Download for free: 77 Picking Exercises for Modern Guitar (Guitar Technique) [Kindle Edition]