I'm really only really interested in buying vegetarian low carb books, what with being a vegetarian. i have bought a lot of book since my diagnosis in February.
Rose Elliot has written 2 differnt low carb cookery books. I have them both and have made things from both of them. The both have some nice recipies in them.
I also have the veggie low carb book by Celia Brooks Brown, who provided me with the recipe for Chocolate Marzipan Cheesecake and Lemon Macaroon Tart. Very nice book and I will be making more of her recipies. Not an easy to get hold of book as it is out of print, but I paid less than £10 for it.
The Veggie low carb book by Margi DeMello is one I don't use very much, I have looked at it but not made anything from it as the recipies are much higher in carbs than the other three I have. Again out of print.
I also have the Soy Zone by Paul Sears, again I have not made anything from it.
The Anthony Worrall-Thompson book is low GI not low carb (and most of his low GI cookery books are approved by DiabetesUK

). My opinion of the Charles Clarke recipies was that they were low GI rather than low carb, although the advice in the "science" part of the book is simple, straightforward and well written.
I look in other low carb books and may copy a recipie. I also surf the net and have found some nice low carb cakes on low carb websites. This website is also excellent for recipies, you must try Larssons caulifower cheese and chocfish's celariac dauphinase
I started by looking at a low GI diet abd acquired several low GI books too. I may start to use them once I have got to where I want to be, but they are too carby for me right now.