Doke Doke is a free creative wordpress theme designed by Luiz Zuno, aka Ansimuz. This has a simple flat design which the author says has been released in time to promote iOS7 apps which have also moved to a flat design and away from the rather ugly apple skeuomorphism. This minimal flat design using bold colours will provide a good backdrop to the app image you use. The product / app image placeholder on the home screen would also work for ebooks and other software products.
You have the ability to add headings, sub headings, buttons and images on the home screen. You also have the option to choose a different frame for the screenshot of your product, app or ebook. It comes with flattened versions of the iphone, ipad and Galaxy S3. You can also remove the home page easily and just display your latest posts.
The inner pages have the option to a right hand side bar and then you can pimp it out with whatever wordpress plugins you want. Recommended for promoting apps/software/ebooks, blogging or showcasing creative work.