Here is one for the wheat free.
http://www.amazon.co.uk/Greatest-Wheat- ... ndle+books
2 day diet book
http://www.amazon.co.uk/DAY-DIET-BOOK-S ... ndle+books
http://www.amazon.co.uk/Top-Class-Low-C ... ndle+books
If you type free kindle books into amazon you will get thousands show up. Go to the left and thin it down to topics etc. There are paleo, duken, vegan and low carb books as well.