I think I remember coming across
http://chrisguillebeau.com/ and was pretty much a blog trying to sell his digital books. One for $50 promising that after reading the book you'd come out with xxx,xxx frequent flyer miles. Basically you are paying someone $50 to then tell you to go earn miles for getting a lasik exam or hair club for men meeting. Spend $6-7 and pick up the Frugal Travel Guy's book which the money will probably go to a better cause in the long run.
Can someone tell me why they call it travel hacking? Sounds like a much cooler name for something that's not that fancy. You really aren't traveling to Europe for free... you are getting to Europe for a very very cheap price. If you have to sign up for credit card offers and spend a few $1k.. that's not exactly "free".