"Ultramarathon Man" is a good book. I really enjoyed reading it - it has a real conversational tone to it. Paul, I try and perform CrossFit in addition to my marathon training and I agree that it helps.
And someone made this point on another thread - I may not be the fastest runner but I know that any non-CF runner who wants to come feast on some CF will be feasting with me and Uncle Pukie. Hah!