I haven't seen any of them, but I doubt they're very useful. I imagine they just go over the standard SEO techniques, perhaps with some case studies or something... It's unlikely that there are any SEO tricks that are only available from the books. There are much better ways to get rid of that extra money you have... give it away on your website, for example. That'll get you some traffic.
And i never think they had anything to offer me. I find maybe 1 tip in each book but i can also spend that time looking at this forum instead.
I agree with you. Many rules in search engines are updated daily, but some books I am not sure they will update them.