Best Free Book: Dan John's "From the Ground Up" - danjohn.org
Totally worth it, even at 10x the price. Seriously, it's a great book.
I also think Tommy Kono's book is excellent. I bought it from him (hey, support the greats!) and loved it. I have been training for about a year with coaches, but I still found his book immediately helpful, useful, and just full of great stuff. Efficient and enjoyable to read.
"Morning, Putski eats it, noon, Putski eats it, night, Putski eats it. Putski loves!"