Better than Logos...
As I have said before, people aren't buying your book, or any of your other products, they are buying YOU. By using Logos or Pictures of a sunset (or whatever) for your blog or website, you are detaching from your audience. A good way to connect with the people you are interested in being interested in you is to use an actual photo (or some variation thereof) of yourself. Here is an article that also may help you to see the benefits of personalization.