Where I find value is when someone helps me find good books that are bargains/free. Rather than hearing about every possible free book (link spam IMO) I would rather hear about ones that were highly rated, or about ones that the poster recommended from their own interest. Or, even a post from an author as long as the book was a bargain (otherwise go to the self-promotion thread). Ideally an affiliate would start with the list of all bargain books and reduce them to those that they recommend.
I like hearing about every possible free book. I like have the choice of viewing all the free books available and pick it or not. I don't want someone else telling me that they liked a book and only list that book. Their taste in reading is not mine.
If I find a deal, or get an code in an email, I will post it here for benefit of anyone who would like it. No benefit to me, just happy to pass on a deal.