Based on my experience, the Pad and Quill cases are the toughest of all the gadget cases which imitate Moleskine notebooks. And now there are finally Kindle 3 and Nook versions.
If the ebook reader cases are as sturdy and durable as the iPhone 4 and iPad versions, then they're great for the clumsy or Moleskine-addicted folks in your life.
You can get either of the ebook reader cases for $45. [Pad and Quill]